JavaScript Daemons Management - Archive of obsolete content
-1 : 1; var bbreak = odmn.task.call(odmn.owner, odmn.index, odmn.length, odmn.backw) === false, bend = odmn.isatend(), binvert = odmn.reversals > 0; if (bend && !binvert || bbreak) { odmn.pause(); return false; } if (bend && binvert) { odmn.backw = !odmn.backw; odmn.reversals--; } return true; }; /* system not required daemon global object methods */ /** * daemon global object optional methods (shortcuts).
... **/ daemon.prototype.start = function (breverse) { var bbackw = boolean(breverse); if (this.backw === bbackw && (this.isatend() || !this.paused)) { return false; } this.backw = bbackw; this.paused = false; if (this.onstart) { this.onstart.call(this.owner, this.index, this.length, this.backw); } this.synchronize(); return true; }; daemon.prototype.stop = function () { this.pause(); if (this.onstop) { this.onstop.call(this.owner, this.index, this.length, this.backw); } delete this.index; delete this.backw; delet...
...-1 : 1; var bbreak = odmn.task.call(odmn.owner, odmn.index, odmn.length, odmn.backw) === false, bend = odmn.isatend(), binvert = odmn.reversals > 0; if (bend && !binvert || bbreak) { odmn.paused = true; return false; } if (bend && binvert) { odmn.backw = !odmn.backw; odmn.reversals--; } odmn.synchronize(); return true; }; /* system not required daemon.safe global object methods */ /** * daemon.safe global object optional m...
...And 12 more matches

Textbox (XPFE autocomplete) - Archive of obsolete content
if false, the default value, the popup will be hidden.
...if false, the default, the value will not be filled in until the user selects an item.
...if false, only the text that hasn't been entered yet will be filled in.
...And 12 more matches

Client-side form validation - Learn web development
if the control is not a candidate for constraint validation (willvalidate is false) or the element's value satisfies its constraints (is valid), this will return an empty string.
...you can find full details of all the available properties in the validitystate reference page; below is listed a few of the more common ones: patternmismatch: returns true if the value does not match the specified pattern, and false if it does match.
... toolong: returns true if the value is longer than the maximum length specified by the maxlength attribute, or false if it is shorter than or equal to the maximum.
...And 12 more matches

nsIPromptService
return value true for ok, false for cancel see also the confirm_example.
... return value true for ok, false for cancel confirmex() puts up a dialog with up to 3 buttons and an optional, labeled checkbox.
... return value true for ok, false for cancel promptusernameandpassword() shows a dialog with an edit field, a password field, and an optional, labeled checkbox.
...And 12 more matches

Linear-gradient Generator - CSS: Cascading Style Sheets
own-list { height: 66px; line-height: 2.5em; overflow: hidden; } #delete-axis { margin: 0 38px 0 0; float: right !important; } /* tool controls */ #tool-section .property .name { width: 150px; } #canvas-bg { width: 16px; height: 16px; margin: 5px; background: url("images/toggle-background.png") center right no-repeat; } #canvas-bg:hover { cursor: pointer; } #canvas-bg[data-alpha='false'] { background-position: center left; } #canvas-bg[data-alpha='true'] { background-position: center right; } /* order gradients */ #order { margin-left: 24px; } #gradient-axes { width: 100%; height: 30px; padding: 0 0 0 15px; display: table; position: relative; } #gradient-axes .axis { width: 50px; height: 20px; margin: 5px 0; background-color: #ddd; text-align: center; float: ...
...' + obj.format; this.lightness = obj.lightness; }; color.prototype.setformat = function setformat(format) { if (format === 'hsv') this.format = 'hsv'; if (format === 'hsl') this.format = 'hsl'; }; /*========== methods to set color properties ==========*/ color.prototype.isvalidrgbvalue = function isvalidrgbvalue(value) { return (typeof(value) === 'number' && isnan(value) === false && value >= 0 && value <= 255); }; color.prototype.setrgba = function setrgba(red, green, blue, alpha) { if (this.isvalidrgbvalue(red) === false || this.isvalidrgbvalue(green) === false || this.isvalidrgbvalue(blue) === false) return; this.r = red | 0; this.g = green | 0; this.b = blue | 0; if (this.isvalidrgbvalue(alpha) === true) this.a = alpha | 0; }; color.
...prototype.setbyname = function setbyname(name, value) { if (name === 'r' || name === 'g' || name === 'b') { if(this.isvalidrgbvalue(value) === false) return; this[name] = value; this.updatehsx(); } }; color.prototype.sethsv = function sethsv(hue, saturation, value) { this.hue = hue; this.saturation = saturation; this.value = value; this.hsvtorgb(); }; color.prototype.sethsl = function sethsl(hue, saturation, lightness) { this.hue = hue; this.saturation = saturation; this.lightness = lightness; this.hsltorgb(); }; color.prototype.sethue = function sethue(value) { if (typeof(value) !== 'number' || isnan(value) === true || value < 0 || value > 359) return; this.hue = value; this.updatergb(); }; color.prototype.setsaturation = function setsa...
...And 12 more matches

source-editor.jsm
r acolumn, [optional] number aalign); void setselection(number astart, number aend); breakpoint management void addbreakpoint(number alineindex, [optional] string acondition); array getbreakpoints(); boolean removebreakpoint(number alineindex); properties attribute type description dirty boolean set this value to false whenever you save the text; the editor will update it to true when the content is changed.
... ignorecase boolean true if the search was case sensitive; otherwise false.
...set it to false to allow editing.
...And 11 more matches

Bytecode Descriptions
false, true stack: ⇒ true/false push a boolean constant.
...otherwise push false.
...implements: propertydefinitionevaluation for methods, steps 3 and 4, when enumerable is false.
...And 11 more matches

nsITreeView
to get the behavior where drops are only allowed on items, such as the mailnews folder pane, always return false when the orientation is not drop_on.
... return value true if a drop is allowed at the current location; otherwise false.
...to get the behavior where drops are only allowed on items, such as the mailnews folder pane, always return false from candropbeforeafter().
...And 11 more matches

Border-image generator - CSS: Cascading Style Sheets
40px !important; } #unit-settings .close { width: 16px; height: 16px; background: url('https://mdn.mozillademos.org/files/6019/close.png') no-repeat center center; background-size: 75%; position: absolute; top: 4px; right: 4px; opacity: 0.5; } #unit-settings .close:hover { cursor: pointer; opacity: 1; } #unit-settings[data-active='true'] { opacity: 1; } #unit-settings[data-active='false'] { opacity: 0; top: -100px !important; } /* * css output code */ #output { padding: 10px; border: 2px dashed #888 !important; box-shadow: none !important; border-radius: 3px; overflow: hidden; -moz-user-select: text; -webkit-user-select: text; -ms-user-select: text; user-select: text; } @media (min-width: 880px) { #output { width: 63.33% !important; } } @media (max-width: ...
...etvalue = function setvalue(topic, value, send_notify) { var slider = sliders[topic]; if (slider === undefined) return; value = parsefloat(value.tofixed(slider.precision)); if (value > slider.max) value = slider.max; if (value < slider.min) value = slider.min; slider.value = value; slider.node.setattribute('data-value', value); slider.setinputvalue(); if (send_notify === false) return; notify.call(slider); }; var setmax = function setmax(topic, value) { var slider = sliders[topic]; if (slider === undefined) return; slider.max = value; setvalue(topic, slider.value); }; var setmin = function setmin(topic, value) { var slider = sliders[topic]; if (slider === undefined) return; slider.min = value; setvalue(topic, slider.value); }; var...
...l) option.setattribute('data-value', uval); list.appendchild(node.firstelementchild); uval++; } node.appendchild(select); node.appendchild(list); select.onclick = this.toggle.bind(this); list.onclick = this.updatevalue.bind(this); document.addeventlistener('click', clickout); this.state = 0; this.time = 0; this.dropmenu = list; this.select = select; this.toggle(false); this.value = {}; this.topic = topic; if (label) select.textcontent = label; else this.setnodevalue(list.children[selected]); dropdowns[topic] = this; }; dropdown.prototype.toggle = function toggle(state) { if (typeof(state) === 'boolean') this.state = state === false ?
...And 11 more matches

Box-shadow generator - CSS: Cascading Style Sheets
true : false; this.topic = topic; this.node = node; var pointer = document.createelement('div'); pointer.classname = 'ui-slider-pointer'; node.appendchild(pointer); this.pointer = pointer; setmousetracking(node, updateslider.bind(this)); sliders[topic] = this; setvalue(topic, this.value); } var setbuttoncomponent = function setbuttoncomponent(node) { var type = node.getattribute('dat...
...var rgb = "(" + this.r + ", " + this.g + ", " + this.b; var a = ''; var v = ''; if (this.a !== 1) { a = 'a'; v = ', ' + this.a; } var value = "rgb" + a + rgb + v + ")"; return value; } color.prototype.getcolor = function getcolor() { if (this.a | 0 === 1) return this.gethexa(); return this.getrgba(); } /** * shadow object */ function shadow() { this.inset = false; this.posx = 5; this.posy = -5; this.blur = 5; this.spread = 0; this.color = new color(); var hue = (math.random() * 360) | 0; var saturation = (math.random() * 75) | 0; var value = (math.random() * 50 + 50) | 0; this.color.sethsv(hue, saturation, value, 1); } shadow.prototype.computecss = function computecss() { var value = ""; if (this.inset === true) val...
...false : true; } shadow.prototype.copy = function copy(obj) { if(obj instanceof shadow !== true) { console.log("typeof instance not shadow"); return; } this.inset = obj.inset; this.posx = obj.posx; this.posy = obj.posy; this.blur = obj.blur; this.spread = obj.spread; this.color.copy(obj.color); } /** * color picker */ var colopicker = (function colopicker() { var colorpicker; v...
...And 11 more matches

Object.defineProperty() - JavaScript
defaults to false.
... defaults to false.
... defaults to false.
...And 11 more matches

JXON - Archive of obsolete content
|*| http://www.gnu.org/licenses/gpl-3.0-standalone.html |*| \*/ function parsetext (svalue) { if (/^\s*$/.test(svalue)) { return null; } if (/^(?:true|false)$/i.test(svalue)) { return svalue.tolowercase() === "true"; } if (isfinite(svalue)) { return parsefloat(svalue); } if (isfinite(date.parse(svalue))) { return new date(svalue); } return svalue; } function jxontree (oxmlparent) { var nattrlen = 0, nlength = 0, scollectedtxt = ""; if (oxmlparent.haschildnodes()) { for (var onode, sprop, vcontent, nitem = 0; nitem < oxmlparent.childnod...
...|*| http://www.gnu.org/licenses/gpl-3.0-standalone.html |*| \*/ function parsetext (svalue) { if (/^\s*$/.test(svalue)) { return null; } if (/^(?:true|false)$/i.test(svalue)) { return svalue.tolowercase() === "true"; } if (isfinite(svalue)) { return parsefloat(svalue); } if (isfinite(date.parse(svalue))) { return new date(svalue); } return svalue; } function jxontree (oxmlparent) { if (oxmlparent.haschildnodes()) { var scollectedtxt = ""; for (var onode, sprop, vcontent, nitem = 0; nitem < oxmlparent.childnodes.length; nitem++) { ...
...|*| http://www.gnu.org/licenses/gpl-3.0-standalone.html |*| \*/ function parsetext (svalue) { if (/^\s*$/.test(svalue)) { return null; } if (/^(?:true|false)$/i.test(svalue)) { return svalue.tolowercase() === "true"; } if (isfinite(svalue)) { return parsefloat(svalue); } if (isfinite(date.parse(svalue))) { return new date(svalue); } return svalue; } function getjxontree (oxmlparent) { var vresult = /* put here the default value for empty nodes!
...And 10 more matches

Tree View Details - Archive of obsolete content
var treeview = { childdata : { solids: ["silver", "gold", "lead"], liquids: ["mercury"], gases: ["helium", "nitrogen"] }, visibledata : [ ["solids", true, false], ["liquids", true, false], ["gases", true, false] ], }; the childdata structure holds an array of the children for each of the three parent nodes.
...obviously, the new inserted child items will have both values set to false.
...unt() { return this.visibledata.length; }, settree: function(treebox) { this.treebox = treebox; }, getcelltext: function(idx, column) { return this.visibledata[idx][0]; }, iscontainer: function(idx) { return this.visibledata[idx][1]; }, iscontaineropen: function(idx) { return this.visibledata[idx][2]; }, iscontainerempty: function(idx) { return false; }, isseparator: function(idx) { return false; }, issorted: function() { return false; }, iseditable: function(idx, column) { return false; }, } the rowcount function will return the length of the visibledata array.
...And 10 more matches

Enc Dec MAC Using Key Wrap CertReq PKCS10 CSR
"-v"); exit(-1); } /* * validate the options used for generate csr command */ static void validategeneratecsrcommand(const char *progname, const char *dbdir, certname *subject, const char *subjectstr, const char *certreqfilename) { prbool validationfailed = pr_false; if (!subject) { pr_fprintf(pr_stderr, "%s -g -d %s -s: improperly formatted name: \"%s\"\n", progname, dbdir, subjectstr); validationfailed = pr_true; } if (!certreqfilename) { pr_fprintf(pr_stderr, "%s -g -d %s -s %s -r: certificate request file name not found\n", progname, dbdir, subjectstr); validationf...
... const char *nicknamestr, const char *truststr, const char *certfilename, const char *certreqfilename, const char *issuernamestr, const char *serialnumberstr, prbool selfsign) { prbool validationfailed = pr_false; if (!nicknamestr) { pr_fprintf(pr_stderr, "%s -a -d %s -n : nick name is missing\n", progname, dbdir); validationfailed = pr_true; } if (!truststr) { pr_fprintf(pr_stderr, "%s -a -d %s -n %s -t: trust flag is missing\n", progname, dbdir, nicknamestr); validationfailed = pr_true; } if (!certfilena...
...mber> [-x <\"\">] \n"); exit(-1); } } /* * validate the options used for save cert to header command */ static void validatesavecerttoheadercommand(const char *progname, const char *dbdir, const char *nicknamestr, const char *headerfilename) { prbool validationfailed = pr_false; if (!nicknamestr) { pr_fprintf(pr_stderr, "%s -s -d %s -n : nick name is missing\n", progname, dbdir); validationfailed = pr_true; } if (!headerfilename) { pr_fprintf(pr_stderr, "%s -s -d %s -n %s -b : header file name is not found\n", progname, dbdir, nicknamestr); validationfailed = pr_true; } ...
...And 10 more matches

OpenClose - Archive of obsolete content
the menu element has an open property which may be set to true to open the menu, or false to close the menu.
... a menu may be closed by a script by setting the open property to false, the reverse of what would be done to open the menu.
... somemenu.open = false; this command will close only a single level of menus, so any parent menus will need to be closed with a similar command if desired.
...And 9 more matches

sample2
- to enable ascii [optional]\n\n", "-a"); fprintf(stderr, "%-30s - to save certificate to header file as sig verification [optional]\n\n", "-v"); exit(-1); } /* * validate the options used for generate csr command */ static void validategeneratecsrcommand(const char *progname, const char *dbdir, certname *subject, const char *subjectstr, const char *certreqfilename) { prbool validationfailed = pr_false; if (!subject) { pr_fprintf(pr_stderr, "%s -g -d %s -s: improperly formatted name: \"%s\"\n", progname, dbdir, subjectstr); validationfailed = pr_true; } if (!certreqfilename) { pr_fprintf(pr_stderr, "%s -g -d %s -s %s -r: certificate request file name not found\n", progname, dbdir, subjectstr); validationfailed = pr_true; } if (validationfailed) { fprintf(stderr, "\nusage: %s %s \n\n", progname,...
...dbdirpath> -s <subject> -r <csr> \n"); exit(-1); } } /* * validate the options used for add cert to db command */ static void validateaddcerttodbcommand(const char *progname, const char *dbdir, const char *nicknamestr, const char *truststr, const char *certfilename, const char *certreqfilename, const char *issuernamestr, const char *serialnumberstr, prbool selfsign) { prbool validationfailed = pr_false; if (!nicknamestr) { pr_fprintf(pr_stderr, "%s -a -d %s -n : nick name is missing\n", progname, dbdir); validationfailed = pr_true; } if (!truststr) { pr_fprintf(pr_stderr, "%s -a -d %s -n %s -t: trust flag is missing\n", progname, dbdir, nicknamestr); validationfailed = pr_true; } if (!certfilename) { pr_fprintf(pr_stderr, "%s -a -d %s -n %s -t %s -c: certificate file name not found\n", progname...
...\nusage: %s %s \n\n", progname, "-a -d <dbdirpath> -n <nickname> -t <trust> -c <cert> -r <csr> -u <issuernickname> -m <serialnumber> [-x <\"\">] \n"); exit(-1); } } /* * validate the options used for save cert to header command */ static void validatesavecerttoheadercommand(const char *progname, const char *dbdir, const char *nicknamestr, const char *headerfilename) { prbool validationfailed = pr_false; if (!nicknamestr) { pr_fprintf(pr_stderr, "%s -s -d %s -n : nick name is missing\n", progname, dbdir); validationfailed = pr_true; } if (!headerfilename) { pr_fprintf(pr_stderr, "%s -s -d %s -n %s -b : header file name is not found\n", progname, dbdir, nicknamestr); validationfailed = pr_true; } if (validationfailed) { fprintf(stderr, "\nusage: %s %s \n\n", progname, "-s -d <dbdirpath> -n <nickn...
...And 9 more matches

Shell global objects
options is an optional object that may have these properties: isrunonce use the isrunonce compiler option (default: false) noscriptrval use the no-script-rval compiler option (default: false) filename filename for error messages and debug info linenumber starting line number for error messages and debug info columnnumber starting column number for error messages and debug info global global in which to execute the code newcontext if true, create and use a new cx (default: false) catchtermin...
... unwrappedobjectshavesameshape(obj1, obj2) returns true iff obj1 and obj2 have the same shape, false otherwise.
...if present, options may have properties saying how the code should be compiled: noscriptrval use the no-script-rval compiler option (default: false) filename filename for error messages and debug info linenumber starting line number for error messages and debug info columnnumber starting column number for error messages and debug info element if present with value v, convert v to an object o and mark the source as being attached to the dom element o.
...And 9 more matches

IAccessibleTable2
return value s_false if there is nothing to return, [out] value is null.
...s_false if there is nothing to return, [out] value is null.
...isselected returns true if the specified column is selected completely and false otherwise.
...And 9 more matches

nsIFile
by default, this value is false on all non-unix systems.
...otherwise it returns false.
...otherwise it returns false.
...And 9 more matches

Equality comparisons and sameness - JavaScript
briefly: double equals (==) will perform a type conversion when comparing two things, and will handle nan, -0, and +0 specially to conform to ieee 754 (so nan != nan, and -0 == +0); triple equals (===) will do the same comparison as double equals (including the special handling for nan, -0, and +0) but without type conversion; if the types differ, false is returned.
...for any non-primitive objects x and y which have the same structure but are distinct objects themselves, all of the above forms will evaluate to false.
... var num = 0; var obj = new string('0'); var str = '0'; console.log(num === num); // true console.log(obj === obj); // true console.log(str === str); // true console.log(num === obj); // false console.log(num === str); // false console.log(obj === str); // false console.log(null === undefined); // false console.log(obj === null); // false console.log(obj === undefined); // false strict equality is almost always the correct comparison operation to use.
...And 9 more matches

Control flow and error handling - JavaScript
use the optional else clause to execute a statement if the condition is false.
... an if statement looks like this: if (condition) { statement_1; } else { statement_2; } here, the condition can be any expression that evaluates to true or false.
... (see boolean for an explanation of what evaluates to true and false.) if condition evaluates to true, statement_1 is executed.
...And 9 more matches

Expressions and operators - JavaScript
logical operators operator usage description logical and (&&) expr1 && expr2 returns expr1 if it can be converted to false; otherwise, returns expr2.
... thus, when used with boolean values, && returns true if both operands are true; otherwise, returns false.
...thus, when used with boolean values, || returns true if either operand is true; if both are false, returns false.
...And 9 more matches

Interacting with page scripts - Archive of obsolete content
in content scripts available to page scripts: // content-script.js unsafewindow.contentscriptobject = {"greeting" : "hello from add-on"}; // page-script.js var button = document.getelementbyid("show-content-script-var"); button.addeventlistener("click", function() { // access object defined by content script console.log(window.contentscriptobject.greeting); // "hello from add-on" }, false); after firefox 30, you can still do this for primitive values, but can no longer do it for objects.
...and the other listener displays a property of the assigned object: <html> <head> </head> <body> <input id="works" type="button" value="i will work"/> <input id="fails" type="button" value="i will not work"/> <script> var works = document.getelementbyid("works"); works.addeventlistener("click", function() { alert(clonedcontentscriptobject.greeting); }, false); var fails = document.getelementbyid("fails"); fails.addeventlistener("click", function() { alert(assignedcontentscriptobject.greeting); }, false); </script> </body> </html> if you run the example, clicking "i will work" displays the value of "greeting" in an alert.
...greetme"}); finally, the "page.html" file adds a button and a page script that calls the exported function when the user pushes the button: <html> <head> </head> <body> <input id="test" type="button" value="click me"/> <script> var test = document.getelementbyid("test"); test.addeventlistener("click", function() { alert(window.greetme("page script")); }, false); </script> </body> </html> exportfunction() works by structured cloning the arguments and return value of the function from one scope to the other.
...And 8 more matches

Tabbed browser - Archive of obsolete content
xul: <menuitem oncommand="myextension.foo(event)" onclick="checkformiddleclick(this, event)" label="click me"/> js: var myextension = { foo: function(event) { openuilink("http://www.example.com", event, false, true); } } opening a url in an on demand tab cu.import("resource://gre/modules/xpcomutils.jsm"); xpcomutils.definelazyservicegetter(this, "gsessionstore", "@mozilla.org/browser/sessionstore;1", "nsisessionstore"); // create new tab, but don't load the content.
... var url = "https://developer.mozilla.org"; var tab = gbrowser.addtab(null, {relatedtocurrent: true}); gsessionstore.settabstate(tab, json.stringify({ entries: [ { title: url } ], usertypedvalue: url, usertypedclear: 2, lastaccessed: tab.lastaccessed, index: 1, hidden: false, attributes: {}, image: null })); reusing tabs rather than open a new browser or new tab each and every time one is needed, it is good practice to try to re-use an existing tab which already displays the desired url--if one is already open.
... function openandreuseonetabperurl(url) { var wm = components.classes["@mozilla.org/appshell/window-mediator;1"] .getservice(components.interfaces.nsiwindowmediator); var browserenumerator = wm.getenumerator("navigator:browser"); // check each browser instance for our url var found = false; while (!found && browserenumerator.hasmoreelements()) { var browserwin = browserenumerator.getnext(); var tabbrowser = browserwin.gbrowser; // check each tab of this browser instance var numtabs = tabbrowser.browsers.length; for (var index = 0; index < numtabs; index++) { var currentbrowser = tabbrowser.getbrowseratindex(index); if (url == currentbrowser.curren...
...And 8 more matches

LiveConnect Overview - Archive of obsolete content
however, suppose myfunction is defined in javascript as follows: function myfunction() { try { if (thecondition == true) { return "everything's ok"; } else { throw "javascript error occurred"; } } catch (e) { if (canhandle == true) { handleit(); } else { throw e; } } } if thecondition is false, the function throws an exception.
...if canhandle is false, the exception is rethrown, the java handler catches it, and the doit method returns a java string: javascript error occurred see exception handling statements for complete information about javascript exceptions.
...for example: 237 becomes "237" boolean 0 and nan values are converted to false.
...And 8 more matches

OS.File for the main thread
txt if the file is located in directory c:\jean\ var promise = os.file.move(os.path.join('c:', 'jean', 'test.txt'), os.path.join('c:', 'jean', 'testrenamed.txt')); promise.then( function() { console.log('rename successful') }, function(arejectreason) { console.log('rename failed, arejectreason = ', arejectreason) } ) the nooverwrite true is important, as default is false which means if a file in the directory exists already with the same name it will no longer be there after this "rename" operation, which is a "move".
...specify append: false to open the file in regular mode.
... when opening files for writing, they will be opened for appending unless you specify append: false in gecko 27 and later.
...And 8 more matches

nsIZipWriter
inqueue boolean true if operations are being performed in the background queue, or false if background operations are not in progress.
...if false, the operation is performed immediately.
...r_create_file: 0x08, pr_append: 0x10, pr_truncate: 0x20, pr_sync: 0x40, pr_excl: 0x80}; zw.open(xpi, pr.pr_wronly | pr.pr_create_file | pr.pr_truncate); //xpi file is created if not there, if it is there it is truncated/deleted var filetoaddtozip = fileutils.file('c:\\add this file.txt'); var saveinzipas = 'blah.txt'; zw.addentryfile(saveinzipas, ci.nsizipwriter.compression_none, filetoaddtozip, false); in the above example, the file ("add this file.txt") located at "c:\add this file.txt" will be added to the zip file "c:\myzipfile.zip", however in the zip file this file ("add this file.txt") will be named "blah.txt".
...And 8 more matches

WebIDL bindings
note: if your object can only be reflected into js by creating it, not by retrieving it from somewhere, you can skip steps 1 and 2 above and instead add 'wrappercache': false to your descriptor.
...otherinstance); [throws] myinterface dosomethingelse(optional long maybenumber); [throws] void dosomethingelse(myinterface otherinstance); void dotheother(any something); void doyetanotherthing(optional boolean actuallydoit = false); static void staticoperation(any arg); }; will require these method declarations: class myclass { void dosomething(int32_t anumber); double dosomething(myclass* aotherinstance); already_addrefed<myinterface> dosomethingelse(optional<int32_t> amaybenumber, errorresult& rv); void dosomethingelse(myclass& aotherinstance, errorresult& rv...
...if init() or tojsvalue() returns false, they will generally set a pending exception on the jscontext; reporting those is the responsibility of the caller.
...And 8 more matches

Loops and iteration - JavaScript
the statements for loops provided in javascript are: for statement do...while statement while statement labeled statement break statement continue statement for...in statement for...of statement for statement a for loop repeats until a specified condition evaluates to false.
...if the value of condition is false, the for loop terminates.
...ngth; i++) { if (selectobject.options[i].selected) { numberselected++; } } return numberselected; } let btn = document.getelementbyid('btn'); btn.addeventlistener('click', function() { alert('number of options selected: ' + howmany(document.selectform.musictypes)); }); </script> do...while statement the do...while statement repeats until a specified condition evaluates to false.
...And 8 more matches

Boolean - JavaScript
if the value is omitted or is 0, -0, null, false, nan, undefined, or the empty string (""), the object has an initial value of false.
... all other values, including any object, an empty array ([]), or the string "false", create an object with an initial value of true.
... do not confuse the primitive boolean values true and false with the true and false values of the boolean object.
...And 8 more matches

Object.isFrozen() - JavaScript
object.isfrozen({}); // === false // an empty object which is not extensible // is vacuously frozen.
...var oneprop = { p: 42 }; object.isfrozen(oneprop); // === false // preventing extensions to the object still doesn't // make it frozen, because the property is still // configurable (and writable).
... object.preventextensions(oneprop); object.isfrozen(oneprop); // === false // ...but then deleting that property makes the object // vacuously frozen.
...And 8 more matches

delete operator - JavaScript
return value true for all cases except when the property is an own non-configurable property, in which case, false is returned in non-strict mode.
...on successful deletion, it will return true, else false will be returned.
...: 'abc', designation: 'developer' } console.log(delete employee.name); // returns true console.log(delete employee.age); // returns true // when trying to delete a property that does // not exist, true is returned console.log(delete employee.salary); // returns true non-configurable properties when a property is marked as non-configurable, delete won't have any effect, and will return false.
...And 8 more matches

Miscellaneous - Archive of obsolete content
</div> <script type="text/javascript"> var elm = document.getelementbyid("scrollarea"); elm.addeventlistener("dommousescroll", function scroll(event){ //event.detail is positive for a downward scroll, negative for an upward scroll alert("scrolling " + event.detail + " lines"); }, false); </script> if you do not receive a dommousescroll event while holding any of the modifier keys (ctrl,shift,alt,meta) you should check the mousewheel.withcontrolkey.action and related preferences.
...note that it returns the empty string (""), not false, when nothing is selected.
... var focusedcontrol; window.addeventlistener("load", function(e) { onwindowload(e); }, false); function onwindowload() { gbrowser.addeventlistener("load", onpageload, true); } function onpageload() { pagedoc = document.commanddispatcher.focusedwindow.document; var inputlist = pagedoc.getelementsbytagname('input'); for (var i=1; i<inputlist.length; i++) { inputlist.item(i).
...And 7 more matches

Visual typescript game engine - Game development
client config if you want web app without any networking then setup: appusenetwork: boolean = false; you want to use communication for multiplayer but you don't want to use server database account sessions.
... the setup this on false in main client config class.
... appuseaccountssystem: boolean = false; networking is disabled by default.
...And 7 more matches

Making decisions in your code — conditionals - Learn web development
the condition makes use of the comparison operators we discussed in the last module and returns true or false.
... another set of curly braces, inside which we have some more code — this can be any code we like, and it only runs if the condition is not true — or in other words, the condition is false.
...te that you don't have to include the else and the second curly brace block — the following is also perfectly legal code: if (condition) { code to run if condition is true } run some other code however, you need to be careful here — in this case, the second block of code is not controlled by the conditional statement, so it always runs, regardless of whether the condition returns true or false.
...And 7 more matches

IAccessibleText
when a method doesn't implement this method it must return s_false.
...s_false if there is nothing to return, [out] values are 0s and null respectively.
... return value s_false if the caret is not currently active on this object, that is the caret is located on some other object.
...And 7 more matches

Web Console remoting - Firefox Developer Tools
when navigation stops the following packet is sent: { "from": tabactor, "type": "tabnavigated", "state": "stop", "url": newurl, "title": newtitle, "nativeconsoleapi": true|false } getcachedmessages(types, onresponse) the webconsoleclient.getcachedmessages(types, onresponse) method sends the following packet to the server: { "to": "conn0.console9", "type": "getcachedmessages", "messagetypes": [ "pageerror", "consoleapi" ] } the getcachedmessages packet allows one to retrieve the cached messages from before the web console was open.
... actor preferences to allow the web console to configure logging options while it is running, we have added the setpreferences packet: { "to": "conn0.console9", "type": "setpreferences", "preferences": { "networkmonitor.saverequestandresponsebodies": false } } reply: { "updated": [ "networkmonitor.saverequestandresponsebodies" ], "from": "conn0.console10" } for convenience you can use webconsoleclient.setpreferences(prefs, onresponse).
... in firefox 25 we added the getpreferences request packet: { "to": "conn0.console34", "type": "getpreferences", "preferences": [ "networkmonitor.saverequestandresponsebodies" ] } reply packet: { "preferences": { "networkmonitor.saverequestandresponsebodies": false }, "from": "conn0.console34" } you can also use the webconsoleclient.getpreferences(prefs, onresponse).
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ARIA: switch role - Accessibility
the two possible values are true and false.
...the switch role does not support the value mixed for the aria-checked attribute; assigning a value of mixed to a switch instead sets the value to false.
...a value of true represents the "on" state; false represents the "off" state; a value of mixed is not supported by the switch role, and is treated as false.
...And 7 more matches

Color picker tool - CSS: Cascading Style Sheets
' + obj.format; this.lightness = obj.lightness; }; color.prototype.setformat = function setformat(format) { if (format === 'hsv') this.format = 'hsv'; if (format === 'hsl') this.format = 'hsl'; }; /*========== methods to set color properties ==========*/ color.prototype.isvalidrgbvalue = function isvalidrgbvalue(value) { return (typeof(value) === 'number' && isnan(value) === false && value >= 0 && value <= 255); }; color.prototype.setrgba = function setrgba(red, green, blue, alpha) { if (this.isvalidrgbvalue(red) === false || this.isvalidrgbvalue(green) === false || this.isvalidrgbvalue(blue) === false) return; this.r = red | 0; this.g = green | 0; this.b = blue | 0; if (this.isvalidrgbvalue(alpha) === true) this.a = alpha | 0; }; color.
...prototype.setbyname = function setbyname(name, value) { if (name === 'r' || name === 'g' || name === 'b') { if(this.isvalidrgbvalue(value) === false) return; this[name] = value; this.updatehsx(); } }; color.prototype.sethsv = function sethsv(hue, saturation, value) { this.hue = hue; this.saturation = saturation; this.value = value; this.hsvtorgb(); }; color.prototype.sethsl = function sethsl(hue, saturation, lightness) { this.hue = hue; this.saturation = saturation; this.lightness = lightness; this.hsltorgb(); }; color.prototype.sethue = function sethue(value) { if (typeof(value) !== 'number' || isnan(value) === true || value < 0 || value > 359) return; this.hue = value; this.updatergb(); }; color.prototype.setsaturation = function setsa...
...this.color); }; colorpicker.prototype.inputchangeblue = function inputchangeblue(e) { var value = parseint(e.target.value); this.color.setbyname('b', value); e.target.value = this.color.b; this.setcolor(this.color); }; colorpicker.prototype.inputchangealpha = function inputchangealpha(e) { var value = parsefloat(e.target.value); if (typeof value === 'number' && isnan(value) === false && value >= 0 && value <= 1) this.color.a = value.tofixed(2); e.target.value = this.color.a; this.updatealphapicker(); }; colorpicker.prototype.inputchangehexa = function inputchangehexa(e) { var value = e.target.value; this.color.sethexa(value); this.setcolor(this.color); }; /*************************************************************************/ // internal pub/...
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Interaction between privileged and non-privileged pages - Archive of obsolete content
var myextension = { mylistener: function(evt) { alert("received from web page: " + evt.target.getattribute("attribute1") + "/" + evt.target.getattribute("attribute2")); } } document.addeventlistener("myextensionevent", function(e) { myextension.mylistener(e); }, false, true); // the last value is a mozilla-specific value to indicate untrusted content is allowed to trigger the event.
...r the alert() in the listener and pass the data from the web page, write code such as this in the web page: var element = document.createelement("myextensiondataelement"); element.setattribute("attribute1", "foobar"); element.setattribute("attribute2", "hello world"); document.documentelement.appendchild(element); var evt = document.createevent("events"); evt.initevent("myextensionevent", true, false); element.dispatchevent(evt); this code creates an arbitrary element -- <myextensiondataelement/> -- and inserts it into the web page's dom.
...e(components.interfaces.nsiwebnavigation) .queryinterface(components.interfaces.nsidocshelltreeitem) .roottreeitem .queryinterface(components.interfaces.nsiinterfacerequestor) .getinterface(components.interfaces.nsidomwindow); mainwindow.document.addeventlistener("myextensionevent", function(e) { myextension.mylistener(e); }, false, true); if you need to to pass lots of data, consider using cdata sections instead of the simple attributes on a custom element.
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Migrate apps from Internet Explorer to Mozilla - Archive of obsolete content
conditionistrue : conditionisfalse; for example, to retrieve an element, you would use: function getelement(aid){ return (document.getelementbyid) ?
...if the boolean is set to false, it will only catch bubbling events.
...internet explorer's event model only has the bubbling phase; therefore, setting the third parameter to false results in internet explorer-like behavior: <div id="mydiv">click me!</div> <script> function handleevent(aevent) { // if aevent is null, it is the internet explorer event model, // so get window.event.
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Desktop gamepad controls - Game development
next, we'll consider the gamepadbuttonpressedhandler() function: function gamepadbuttonpressedhandler(button) { var press = false; for(var i=0; i<buttonspressed.length; i++) { if(buttonspressed[i] == button) { press = true; } } return press; } the function takes a button as a parameter; in the loop it checks if the given button's number is among the currently pressed buttons available in the buttonspressed array.
... if it is, then the function returns true; false otherwise.
...here's the gamepadapi object, which contains useful variables and functions: var gamepadapi = { active: false, controller: {}, connect: function(event) {}, disconnect: function(event) {}, update: function() {}, buttons: { layout: [], cache: [], status: [], pressed: function(button, state) {} } axes: { status: [] } }; the controller variable stores the information about the connected gamepad, and there's an active boolean variable we...
...And 6 more matches

Creating our first Vue component - Learn web development
<template> <div> <input type="checkbox" id="todo-item" checked="false" /> <label for="todo-item">my todo item</label> </div> </template> using todoitem inside our app this is all fine, but we haven’t added the component to our app yet, so there’s no way to test it and see if everything is working.
... first add a default field, with a value of false.
... this means that when no done prop is passed to a todoitem component, the done prop will will have a value of false (bear in mind that this is not required — we only need default on non-required props).
...And 6 more matches

JS::CompileOptions
returns false if it failed to duplicate owning properties.
...returns false if it failed to duplicate.
...returns false if it failed to duplicate.
...And 6 more matches

nsITextInputProcessor
createinstance(components.interfaces.nsitextinputprocessor); next, you need to get the rights to create composition or dispatch keyboard events with begininputtransaction() or begininputtransactionfortests(): if (!tip.begininputtransaction(window, callback)) { return; } if begininputtransaction() or begininputtransactionfortests() returns false, it means that another instance of nsitextinputprocessor has composition on the window or is dispatching an event.
...however, if the event is consumed by web content, it returns false.
... repeat: false, // optional.
...And 6 more matches

Debugger.Object - Firefox Developer Tools
callable true if the referent is a callable object (such as a function or a function proxy); false otherwise.
... isboundfunction if the referent is a debuggee function, returns true if the referent is a bound function; false otherwise.
... isarrowfunction if the referent is a debuggee function, returns true if the referent is an arrow function; false otherwise.
...And 6 more matches

ValidityState - Web APIs
patternmismatch read only a boolean that is true if the value does not match the specified pattern, and false if it does match.
... rangeoverflow read only a boolean that is true if the value is greater than the maximum specified by the max attribute, or false if it is less than or equal to the maximum.
... rangeunderflow read only a boolean that is true if the value is less than the minimum specified by the min attribute, or false if it is greater than or equal to the minimum.
...And 6 more matches

WindowOrWorkerGlobalScope.setInterval() - Web APIs
<!doctype html> <html> <head> <meta charset="utf-8" /> <title>javascript typewriter - mdn example</title> <script> function typewriter (sselector, nrate) { function clean () { clearinterval(nintervid); btyping = false; bstart = true; ocurrent = null; asheets.length = nidx = 0; } function scroll (osheet, npos, beraseandstop) { if (!osheet.hasownproperty('parts') || amap.length < npos) { return true; } var orel, bexit = false; if (amap.length === npos) { amap.push(0); } while (amap[npos] < osheet.parts.length) { orel = osheet.parts[amap[npos]]; scroll(orel, npos +...
...amap[npos]++ : bexit = true; if (beraseandstop && (orel.ref.nodetype - 1 | 1) === 3 && orel.ref.nodevalue) { bexit = true; ocurrent = orel.ref; spart = ocurrent.nodevalue; ocurrent.nodevalue = ''; } osheet.ref.appendchild(orel.ref); if (bexit) { return false; } } amap.length--; return true; } function typewrite () { if (spart.length === 0 && scroll(asheets[nidx], 0, true) && nidx++ === asheets.length - 1) { clean(); return; } ocurrent.nodevalue += spart.charat(0); spart = spart.slice(1); } function sheet (onode) { this.ref = onode; if (!onode.haschildnodes()) { return; } this.parts = array.prototype.slice.call(onode.childnodes); for (var nchild = 0; nchild < this.p...
...arts.length; nchild++) { onode.removechild(this.parts[nchild]); this.parts[nchild] = new sheet(this.parts[nchild]); } } var nintervid, ocurrent = null, btyping = false, bstart = true, nidx = 0, spart = "", asheets = [], amap = []; this.rate = nrate || 100; this.play = function () { if (btyping) { return; } if (bstart) { var aitems = document.queryselectorall(sselector); if (aitems.length === 0) { return; } for (var nitem = 0; nitem < aitems.length; nitem++) { asheets.push(new sheet(aitems[nitem])); /* uncomment the following line if you have previously hidden your elements via css: */ // aitems[nitem].style.visibility = "visible"; } bstart = false; } nintervid = setinterval(typewrite, thi...
...And 6 more matches

<mo> - MathML
allowed values are true or false.
... allowed values are true or false.
...allowed values are either true or false.
...And 6 more matches

util/array - Archive of obsolete content
globals functions has(array, element) returns true if the given array contains the element or false otherwise.
... let { has } = require('sdk/util/array'); let a = ['rock', 'roll', 100]; has(a, 'rock'); // true has(a, 'rush'); // false has(a, 100); // true parameters array : array the array to search.
... hasany(array, elements) returns true if the given array contains any of the elements in the elements array, or false otherwise.
...And 5 more matches

panel - Archive of obsolete content
if set to false, the rollup event is not consumed.
... ignorekeys type: boolean if false, the default value, the escape key may be used to close the panel.
... noautofocus type: boolean if false, the default value, the currently focused element will be unfocused whenever the popup is opened or closed.
...And 5 more matches

XForms Input Element - Archive of obsolete content
the default value is 'false'.
...if "false", or the incremental attribute is omitted on this element then the bound instance node will be updated when the control loses the focus.
... checkbox most often used when the form author only needs a simple 'true', 'false', '1', or '0' response from the user (xhtml/xul).
...And 5 more matches

Working with Svelte stores - Learn web development
add the following import statement below the existing ones: import { alert } from '../stores.js' update your addtodo() function like so: function addtodo(name) { todos = [...todos, { id: newtodoid, name, completed: false }] $alert = `todo '${name}' has been added` } update removetodo() like so: function removetodo(todo) { todos = todos.filter(t => t.id !== todo.id) todosstatus.focus() // give focus to status heading $alert = `todo '${todo.name}' has been deleted` } update the updatetodo() function to this: function updatetodo(todo) { const i = todos.findindex(t => t.id ==...
... update the <script> section of your alert.svelte component like so: <script> import { ondestroy } from 'svelte' import { alert } from '../stores.js' export let ms = 3000 let visible let timeout const onmessagechange = (message, ms) => { cleartimeout(timeout) if (!message) { // hide alert if message is empty visible = false } else { visible = true // show alert if (ms > 0) timeout = settimeout(() => visible = false, ms) // and hide it after ms milliseconds } } $: onmessagechange($alert, ms) // whenever the alert store or the ms props changes run onmessagechange ondestroy(()=> cleartimeout(timeout)) // make sure we clean-up the tim...
...eout </script> and update the alert.svelte markup section like so: {#if visible} <div on:click={() => visible = false}> <svg xmlns="http://www.w3.org/2000/svg" viewbox="0 0 20 20"><path d="m12.432 0c1.34 0 2.01.912 2.01 1.957 0 1.305-1.164 2.512-2.679 2.512-1.269 0-2.009-.75-1.974-1.99c9.789 1.436 10.67 0 12.432 0zm8.309 20c-1.058 0-1.833-.652-1.093-3.524l1.214-5.092c.211-.814.246-1.141 0-1.141-.317 0-1.689.562-2.502 1.117l-.528-.88c2.572-2.186 5.531-3.467 6.801-3.467 1.057 0 1.233 1.273.705 3.23l-1.391 5.352c-.246.945-.141 1.271.106 1.271.317 0 1.357-.392 2.379-1.207l.6.814c12.098 19.02 9.365 20 8.309 20z"/></svg> <p>{ $alert }</p> </div> {/if} here we first create the prop ms with a default value of 3000 (milliseconds).
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Using the Browser API
we did this with the following functions: function canmovebwd() { var request = browser.getcangoback(); request.onsuccess = function() { if (request.result) { back.disabled = false; console.log("it's possible to navigate the history backward."); } else { back.disabled = true; console.log("it's not possible to navigate the history backward."); } } } function canmovefwd() { var request = browser.getcangoforward(); request.onsuccess = function() { if (request.result) { fwd.disabled = false; console.log("it's possible to navigat...
...if true is returned, the relevant button is disabled, and if false is returned, the relevant button is enabled.
...for example: function canmovebwd() { browser.getcangoback().then(function(result) { if (result) { back.disabled = false; console.log("it's possible to navigate the history backward."); } else { back.disabled = true; console.log("it's not possible to navigate the history backward."); } }); } implementing the url bar the url bar for our simple browser is a <form> containing a single text <input>.
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IAccessible2
[propget] hresult attributes( [out] bstr attributes ); parameters attributes return value s_false returned if there is nothing to return, [out] value is null.
...[propget] hresult extendedrole( [out] bstr extendedrole ); parameters extendedrole return value s_false if there is nothing to return, [out] value is null.
... return value s_false if there are no states, [out] values are null and 0 respectively.
...And 5 more matches

Background Tasks API - Web APIs
window.requestidlecallback = window.requestidlecallback || function(handler) { let starttime = date.now(); return settimeout(function() { handler({ didtimeout: false, timeremaining: function() { return math.max(0, 50.0 - (date.now() - starttime)); } }); }, 1); } if window.requestidlecallback is undefined, we create it here.
...the callback is passed an object which conforms to idledeadline, with didtimeout set to false and a timeremaining() method which is implemented to give the callback 50 milliseconds of time to begin with.
... let logfragment = null; let statusrefreshscheduled = false; finally, we set up a couple of variables for other items: logfragment will be used to store a documentfragment that's generated by our logging functions to create content to append to the log when the next animation frame is rendered.
...And 5 more matches

DirectoryEntrySync - Web APIs
create: true exclusive: false path doesn't exist and no other error occurs a file is created.
... create: false (exclusive is ignored) path exists the file is returned.
... create: false (exclusive is ignored) path doesn't exist an error is thrown.
...And 5 more matches

FileSystemDirectoryEntry.getDirectory() - Web APIs
the fileerror.code specifies what type of error occurred, as follows: fileerror.not_found_err the create option was not specified (or was specified as false), and the directory doesn't exist.
...the default is false.
...the default is false.
...And 5 more matches

FileSystemDirectoryEntry.getFile() - Web APIs
the {domxref("fileerror.code")}} specifies what type of error occurred, as follows: fileerror.not_found_err the create option was not specified (or was specified as false), and the file doesn't exist.
...the default is false.
...the default is false.
...And 5 more matches

Ajax navigation example - Web APIs
first_page.php: <?php $page_title = "first page"; $as_json = false; if (isset($_get["view_as"]) && $_get["view_as"] == "json") { $as_json = true; ob_start(); } else { ?> <!doctype html> <html> <head> <?php include "include/header.php"; echo "<title>" .
... if ($as_json) { echo json_encode(array("page" => $page_title, "content" => ob_get_clean())); } else { ?> </div> <p>this paragraph is shown only when the navigation starts from <strong>first_page.php</strong>.</p> <?php include "include/after_content.php"; echo "</body>\n</html>"; } ?> second_page.php: <?php $page_title = "second page"; $as_json = false; if (isset($_get["view_as"]) && $_get["view_as"] == "json") { $as_json = true; ob_start(); } else { ?> <!doctype html> <html> <head> <?php include "include/header.php"; echo "<title>" .
... include/header.php: <meta http-equiv="content-type" content="text/html; charset=utf-8" /> <script type="text/javascript" src="js/ajax_nav.js"></script> <link rel="stylesheet" href="css/style.css" /> js/ajax_nav.js: "use strict"; const ajaxrequest = new (function () { function closereq () { oloadingbox.parentnode && document.body.removechild(oloadingbox); bisloading = false; } function abortreq () { if (!bisloading) { return; } oreq.abort(); closereq(); } function ajaxerror () { alert("unknown error."); } function ajaxload () { var vmsg, nstatus = this.status; switch (nstatus) { case 200: vmsg = json.parse(this.responsetext); document.title = opagei...
...And 5 more matches

Navigator.onLine - Web APIs
the property returns a boolean value, with true meaning online and false meaning offline.
...for example, the property should return false when users click links soon after they lose internet connection.
...so while you can assume that the browser is offline when it returns a false value, you cannot assume that a true value necessarily means that the browser can access the internet.
...And 5 more matches

Movement, orientation, and motion: A WebXR example - Web APIs
the code looks like this: const xrotationdegreespersecond = 25; const yrotationdegreespersecond = 15; const zrotationdegreespersecond = 35; const enablerotation = true; const allowmouserotation = true; const allowkeyboardmotion = true; const enableforcepolyfill = false; //const session_type = "immersive-vr"; const session_type = "inline"; const mouse_speed = 0.003; xrotationdegreespersecond the number of degrees of rotation to apply around the x axis per second.
...if false, only xr device changes to the view are permitted.
...if false, the polyfill is only used if the browser doesn't implement navigator.xr.
...And 5 more matches

ARIA: grid role - Accessibility
the default value is false.
...the default value is false.
...ewcol) { var tgt = document.queryselector('[data-row="' + newrow + '"][data-col="' + newcol + '"]'); if (tgt && (tgt.getattribute('role')==='gridcell') ) { array.prototype.foreach.call(document.queryselectorall('[role=gridcell]'), function(el, i){ el.setattribute('tabindex', '-1'); }); tgt.setattribute('tabindex', '0'); tgt.focus(); return true; } else { return false; } } document.queryselector('table').addeventlistener("keydown", function(event) { switch (event.key) { case "arrowright": moveto(parseint(event.target.dataset.row, 10), parseint(event.target.dataset.col, 10) + 1); break; case "arrowleft": moveto(parseint(event.target.dataset.row, 10), parseint(event.target.dataset.col, 10) - 1); break; case "arrowdown": ...
...And 5 more matches

ARIA: button role - Accessibility
<div id="savechanges" tabindex="0" role="button" aria-pressed="false">save</div> the above example creates a simple button which is first in the focus order, though <button> or <input> with type="button" should be used for buttons: <button id="savechanges">save</button> note: if using role="button" instead of the semantic <button> or <input type="button"> elements, you will need to make the element focusable and have to define event handlers for click and keydown events, including the enter and space key...
...the aria-pressed attribute values of true or false identify a button as a toggle button.
...the values include aria-pressed="false" when a button is not currently pressed, aria-pressed="true" to indicate a button is currently pressed, and aria-pressed="mixed" if the button is considered to be partially pressed.
...And 5 more matches

Comparing Reflect and Object methods - JavaScript
reflect.defineproperty() returns true if the property was defined on the object and false if it was not.
... n/a set() n/a reflect.set() returns true if the property was set successfully on the object and false if it was not.
... deleteproperty() n/a reflect.deleteproperty() returns true if the property was deleted from the object and false if it was not.
...And 5 more matches

isNaN() - JavaScript
return value true if the given value is nan; otherwise, false.
... description the necessity of an isnan function unlike all other possible values in javascript, it is not possible to rely on the equality operators (== and ===) to determine whether a value is nan or not, because both nan == nan and nan === nan evaluate to false.
...thus for non-numbers that when coerced to numeric type result in a valid non-nan numeric value (notably the empty string and boolean primitives, which when coerced give numeric values zero or one), the "false" returned value may be unexpected; the empty string, for example, is surely "not a number." the confusion stems from the fact that the term, "not a number", has a specific meaning for numbers represented as ieee-754 floating-point values.
...And 5 more matches

Communicating With Other Scripts - Archive of obsolete content
finally, "listen.html" uses window.addeventlistener() to listen for messages from the content script: <!doctype html> <html> <head></head> <body> <script> window.addeventlistener('message', function(event) { window.alert(event.data); // message from content script }, false); </script> </body> </html> messaging from page script to content script sending messages from the page script to the content script is just the same, but in reverse.
... "http://my-domain.org/"); } </script> <button onclick="sendmessage()">send message</button> </body> </html> finally, the content script "listen.js" uses window.addeventlistener() to listen for messages from the page script: // listen.js window.addeventlistener('message', function(event) { console.log(event.data); // message from page script console.log(event.origin); }, false); using postmessage() before firefox 31 if your add-on is running in a version of firefox before firefox 31, then your content script can't access the postmessage() or addeventlistener() apis using window, but must access them using document.defaultview instead.
... so the content scripts in the above examples need to be rewritten like this: // content-script.js document.defaultview.postmessage("message from content script", "http://my-domain.org/"); // content-script.js document.defaultview.addeventlistener('message', function(event) { console.log(event.data); // message from page script console.log(event.origin); }, false); using custom dom events as an alternative to using postmessage() you can use custom dom events to communicate between page scripts and content scripts.
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panel - Archive of obsolete content
n", icon: { "16": "./icon-16.png", "32": "./icon-32.png", "64": "./icon-64.png" }, onchange: handlechange }); var mypanel = sdkpanels.panel({ contenturl: self.data.url("panel.html"), onhide: handlehide }); function handlechange(state) { if (state.checked) { mypanel.show({ position: button }); } } function handlehide() { button.state('window', {checked: false}); } updating panel content you can update the panel's content by: sending a message to a content script that updates the dom in the same document.
... var myscript = "window.addeventlistener('click', function(event) {" + " var t = event.target;" + " if (t.nodename == 'a')" + " self.port.emit('click-link', t.tostring());" + "}, false);" var mypanel = require("sdk/panel").panel({ contenturl: "http://www.bbc.co.uk/mobile/index.html", contentscript: myscript }); mypanel.port.on("click-link", function(url) { console.log(url); }); mypanel.show(); this example uses contentscript to supply the script as a string.
... text = textarea.value.replace(/(\r\n|\n|\r)/gm,""); self.port.emit("text-entered", text); textarea.value = ''; } }, false); // listen for the "show" event being sent from the // main add-on code.
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platform/xpcom - Archive of obsolete content
getservice(ci.nsiobserverservice); var starobserver = class({ extends: unknown, interfaces: [ 'nsiobserver' ], topic: '*', register: function register() { observerservice.addobserver(this, this.topic, false); }, unregister: function() { observerservice.removeobserver(this, this.topic); }, observe: function observe(subject, topic, data) { console.log('star observer:', subject, topic, data); } }); var starobserver = starobserver(); starobserver.register(); implementing xpcom factories the xpcom module exports a class called factory which implements the nsifactory interface.
... you can override this behavior using the register and unregister options to the factory or service constructor: var xpcom = require('sdk/platform/xpcom'); var factory = xpcom.factory({ contract: contractid, component: helloworld, register: false, unregister: false, }); if you disable automatic registration in this way, you can use the register() function to register factories and services: xpcom.register(factory); you can use the corresponding unregister() function to unregister them, whether or not you have disabled automatic unregistration: xpcom.unregister(factory); you can find out whether a factory or service has been registe...
...by including this option, set to false, the factory is not automatically registered and you must register it manually using the register() function.
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MCD, Mission Control Desktop, AKA AutoConfig - Archive of obsolete content
[root@calaz firefox]# cat firefox.cfg //put everything in a try/catch try { //privacy & security defaultpref("signon.remembersignons", false); //proxy and cache, as it is on nfs volume, we don't want cache lockpref("browser.cache.disk.capacity", 0); lockpref("network.cookie.cookiebehavior", 0); defaultpref("network.proxy.autoconfig_url", "http://wpad.int-evry.fr/wpad.dat"); defaultpref("network.proxy.type", 2); lockpref("network.protocol-handler.app.mailto", "/usr/bin/thunderbird"); //firefox3 urlclassifier3.sqlite iowait/cpu pb //h...
...ttp://forums.mozillazine.org/viewtopic.php?p=3381133#3381133 defaultpref("browser.safebrowsing.enabled", false); defaultpref("browser.safebrowsing.malware.enabled", false); // 1) env variables if(getenv("user") != "") { // *nix settings var env_user = getenv("user"); var env_home = getenv("home"); } else { // windows settings var env_user = getenv("username"); var env_home = getenv("homepath"); } var env_mozdebug= getenv("mozilla_debug"); // 2) define here (because if set after "3)" below it doesn't work !) processldapvalues which is eventually called by getldapattributes() just below, // check getldapattributes() code from $mozilla_home/defaults/autoconfig/prefcalls.js to see the inside call to "user defined" processldapvalues /* commented all this secti...
... [root@b008-02 /usr/lib/firefox-1.5.0.2] $cat firefox.cfg //put everything in a try/catch try { //privacy & security defaultpref("signon.remembersignons", false); // 1) env variables if(getenv("user") != "") { // *nix settings var env_user = getenv("user"); var env_home = getenv("home"); } else { // windows settings var env_user = getenv("username"); var env_home = getenv("homepath"); } var env_mozdebug = getenv("mozilla_debug"); /* 2) define here (because if set after "3)" below it doesn't work!) processldapvalues which is eventually calle...
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Download Manager preferences - Archive of obsolete content
default value is false.
... in other applications the default value is false.
... in firefox,thunderbird and seamonkey the default value is false.
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Using microformats - Archive of obsolete content
the default is false.
... debug specify true if debug mode is in use; otherwise, specify false.
... the default is false.
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textbox - Archive of obsolete content
do not set the attribute to true, as this will suggest you can set it to false to enable the element again, which is not the case.
...the default value is false.
...if false, the textbox only allows entry of one line.
...And 4 more matches

tree - Archive of obsolete content
<treecell label="joe@somewhere.com"/> <treecell label="top secret plans"/> </treerow> </treeitem> <treeitem> <treerow> <treecell label="mel@whereever.com"/> <treecell label="let's do lunch"/> </treerow> </treeitem> </treechildren> </tree> a tree with several columns and nested items <tree id="mytree" flex="1" hidecolumnpicker="false" seltype="single" class="tree" rows="5"> <treecols id="mytree2-treecols"> <treecol id="mytree2-treecol0" primary="true" flex="2" label="column a" persist="width" ordinal="1"/> <splitter class="tree-splitter" ordinal="2"/> <treecol id="mytree2-treecol1" flex="1" label="column b" persist="width" ordinal="3"/> </treecols> <treechildren> <treeitem...
...do not set the attribute to true, as this will suggest you can set it to false to enable the element again, which is not the case.
... hidecolumnpicker type: boolean when set to false, a drop-down will appear in the upper right corner of the tree, which the user may use to show and hide columns.
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NPClass - Archive of obsolete content
returns true if the method exists, otherwise returns false.
...returns true if invocation succeeded or false if an error occurred.
...returns true if invocation succeeded or false if an error occurred.
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Drawing graphics - Learn web development
let's add an arc to our canvas — add the following to the bottom of your code: ctx.fillstyle = 'rgb(0, 0, 255)'; ctx.beginpath(); ctx.arc(150, 106, 50, degtorad(0), degtorad(360), false); ctx.fill(); arc() takes six parameters.
...the third is the circle's radius, the fourth and fifth are the start and end angles at which to draw the circle (so specifying 0 and 360 degrees gives us a full circle), and the sixth parameter defines whether the circle should be drawn counterclockwise (anticlockwise) or clockwise (false is clockwise).
...if you were to change true to false and then re-run the code, only the 90 degree slice of the circle would be drawn.
...And 4 more matches

React interactivity: Editing, filtering, conditional rendering - Learn web development
first, import usestate into the todo component like we did before with the app component, by updating the first import statement to this: import react, { usestate } from "react"; we'll now use this to set an isediting state, the default state of which should be false.
... add the following line just inside the top of your todo(props) { … } component definition: const [isediting, setediting] = usestate(false); next, we're going to rethink the <todo /> component — from now on, we want it to display one of two possible “templates", rather than the single template it's used so far: the "view" template, when we are just viewing a todo; this is what we’ve used in rest of the tutorial so far.
...to see the editing template, you will have to change the default isediting state from false to true in your code for now; we will look at making the edit button toggle this in the next section!
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Vue conditional rendering: editing existing todos - Learn web development
add isediting below your existing isdone data point: data() { return { isdone: this.done, isediting: false }; } now add your methods inside a methods property, right below your data() property: methods: { deletetodo() { this.$emit('item-deleted'); }, toggletoitemeditform() { this.isediting = true; } } conditionally displaying components via v:if and v:else now we have an isediting flag that we can use to signify that the item is being edited (or not).
...this method should take the new item label as an argument, emit an itemedited event to the parent component, and set isediting to false.
... add it now, below your existing methods: itemedited(newlabel) { this.$emit('item-edited', newlabel); this.isediting = false; } next, we'll need an editcancelled() method.
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Download
this property can become true, then it can be reset to false when a canceled download is restarted.
... this property becomes true as soon as the cancel() method is called, though the stopped property might remain false until the cancellation request has been processed.
...this property becomes false when a download is started for the first time, or when a failed or canceled download is restarted.
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AsyncTestUtils extended framework
your test functions need to agree to the following contract: the asynchronous function contract a function should yield false or return false when something asynchronous is going on.
...returning false tells the asynchronous driver that it should yield control up to the top-level.
... manipulating messages setread(aberead) setread(true) marks all the messages in the set as read, setread(false) marks them as unread.
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Places Developer Guide
}, onendupdatebatch: function() { this._inbatch = false; }, onitemadded: function(id, folder, index) { }, onitemremoved: function(id, folder, index) { }, onitemchanged: function(id, property, isannotationproperty, value) { // isannotationproperty is a boolean value that is true of the changed property is an annotation.
... }, queryinterface: function(iid) { if (iid.equals(ci.nsinavbookmarkobserver) || iid.equals(ci.nsisupports)) { return this; } throw cr.ns_error_no_interface; }, }; // register the observer with the bookmarks service var bmsvc = cc["@mozilla.org/browser/nav-bookmarks-service;1"] .getservice(ci.nsinavbookmarksservice); bmsvc.addobserver(observer, false); // un-register the observer when done.
... getservice(ci.nsinavhistoryservice); var oururi = uri("http://www.mozilla.com"); var visitdate = date.now() * 1000; // in microseconds var referreruri = null; // or a uri var isredirect = false; var visittype = history.transition_link; // the visit is from a link that was clicked var sessionid = 0; // can link the visit with a specific browsing session history.addvisit(oururi, visitdate, referreruri, visittype, isredirect, sessionid); // add a visit to a url, with a page title and visited time // via nsibrowserhistory.
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nsIDOMWindowUtils
true if it's open, otherwise false.
... paintingsuppressed boolean true if painting is currently suppressed for this window; otherwise false.
...if false, this method returns null for coordinates outside of the viewport.
...And 4 more matches

nsIMsgMessageService
false leaves it as just a copy.
...false leaves it as just a copy.
... ageneratedummyenvelope usually false.
...And 4 more matches

nsINavHistoryContainerResultNode
etails(in autf8string auristring, in prtime atime, in long long aitemid, in boolean arecursive); nsinavhistoryresultnode getchild(in unsigned long aindex); unsigned long getchildindex(in nsinavhistoryresultnode anode); attributes attribute type description childcount unsigned long the number of child nodes; accessing this throws an ns_error_not_available exception of containeropen is false.
... childrenreadonly boolean false if the node's list of children can be modified (by adding or removing children, or rearranging them), or true if the user interface should not allow the list of children to be altered.
...this is false for bookmark folder nodes unless the setfolderreadonly() method has been called to specifically make the folder read-only.
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Setting HTTP request headers
// adds "x-hello: world" header to the request httpchannel.setrequestheader("x-hello", "world", false); in the example code above we have a variable named httpchannel which points to an object implementing nsihttpchannel.
...and for now, just ignore the third parameter, and just always make it false.
...is an example observer that adds a custom header "x-hello" to the channel passed in for http-on-modify-request notification: var {cc, ci} = require("chrome"); var httprequestobserver = { observe: function(subject, topic, data) { if (topic == "http-on-modify-request") { var httpchannel = subject.queryinterface(ci.nsihttpchannel); httpchannel.setrequestheader("x-hello", "world", false); } } }; note: the above code was changed to reflect that in a firefox add-on one can not directly access components.interfaces und components.classes anymore but must use the require line introduced to the sample code above.
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Address Book examples
let card = collection.getcardfromproperty("jobtitle", "software engineer", false); if you are searching for a card with a particular email address, you can use the cardforemailaddress function that will match against multiple email addresses stored in one card.
... .createinstance(components.interfaces.nsiabdirectory); maillist.ismaillist = true; now fill in the details you want to store: maillist.dirname = "my mailing list"; maillist.listnickname = "nickname for list"; maillist.description = "list description"; add the cards you want to include in the list: for (let i = 0; i < numcards; i++) maillist.addresslists.appendelement(card[i], false); now save the list: var parentdirectory = ...; // an nsiabdirectory for the parent of the mailing list.
...get the equivalent mailing list object that implements nsiabdirectory: let abmanager = components.classes["@mozilla.org/abmanager;1"] .getservice(components.interfaces.nsiabmanager); let maillistdirectory = abmanager.getdirectory(maillistcard.maillisturi); you can then adjust the items in the actual mailing list: maillistdirectory.addresslists.appendelement(newcard, false); then save the updated list to the database: maillistdirectory.editmaillisttodatabase(maillistcard); deleting a mailing list there are two ways to delete a mailing list.
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Using files from web applications - Web APIs
you need to use eventtarget.addeventlistener() to add the change event listener, like this: const inputelement = document.getelementbyid("input"); inputelement.addeventlistener("change", handlefiles, false); function handlefiles() { const filelist = this.files; /* now you can work with the file list */ } getting information about selected file(s) the filelist object provided by the dom lists all of the files selected by the user, each specified as a file object.
...prox = nbytes / 1024; napprox > 1; napprox /= 1024, nmultiple++) { soutput = napprox.tofixed(3) + " " + amultiples[nmultiple] + " (" + nbytes + " bytes)"; } // end of optional code document.getelementbyid("filenum").innerhtml = nfiles; document.getelementbyid("filesize").innerhtml = soutput; } document.getelementbyid("uploadinput").addeventlistener("change", updatesize, false); </script> </body> </html> using hidden file input elements using the click() method you can hide the admittedly ugly file <input> element and present your own interface for opening the file picker and displaying which file or files the user has selected.
...<input type="file" id="fileelem" multiple accept="image/*" style="display:none"> <button id="fileselect">select some files</button> the code that handles the click event can look like this: const fileselect = document.getelementbyid("fileselect"), fileelem = document.getelementbyid("fileelem"); fileselect.addeventlistener("click", function (e) { if (fileelem) { fileelem.click(); } }, false); you can style the new button for opening the file picker as you wish.
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FileSystemFlags - Web APIs
the default is false.
...the default is false.
... option values file/directory condition result create exclusive false n/a[1] path exists and matches the desired type (depending on whether the function called is getfile() or getdirectory() the successcallback is called with a filesystemfileentry if getfile() was called or a filesystemdirectoryentry if getdirectory() was called.
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Advanced techniques: Creating and sequencing audio - Web APIs
r="release">release</label> <input name="release" id="release" type="range" min="0" max="1" value="0.5" step="0.1" /> now we can create some variables over in javascript and have them change when the input values are updated: let attacktime = 0.2; const attackcontrol = document.queryselector('#attack'); attackcontrol.addeventlistener('input', function() { attacktime = number(this.value); }, false); let releasetime = 0.5; const releasecontrol = document.queryselector('#release'); releasecontrol.addeventlistener('input', function() { releasetime = number(this.value); }, false); the final playsweep() function now we can expand our playsweep() function.
... let pulsehz = 880; const hzcontrol = document.queryselector('#hz'); hzcontrol.addeventlistener('input', function() { pulsehz = number(this.value); }, false); let lfohz = 30; const lfocontrol = document.queryselector('#lfo'); lfocontrol.addeventlistener('input', function() { lfohz = number(this.value); }, false); the final playpulse() function here's the entire playpulse() function: let pulsetime = 1; function playpulse() { let osc = audioctx.createoscillator(); osc.type = 'sine'; osc.frequency.setvalueattime(pulsehz, audioctx.cur...
...uration</label> <input name="duration" id="duration" type="range" min="0" max="2" value="1" step="0.1" /> <label for="band">band</label> <input name="band" id="band" type="range" min="400" max="1200" value="1000" step="5" /> let noiseduration = 1; const durcontrol = document.queryselector('#duration'); durcontrol.addeventlistener('input', function() { noiseduration = number(this.value); }, false); let bandhz = 1000; const bandcontrol = document.queryselector('#band'); bandcontrol.addeventlistener('input', function() { bandhz = number(this.value); }, false); the final playnoise() function here's the entire playnoise() function: function playnoise() { const buffersize = audioctx.samplerate * noiseduration; // set the time of the note const buffer = audioctx.createbuffer(1, ...
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JavaScript data types and data structures - JavaScript
boolean type boolean represents a logical entity and can have two values: true and false.
... undefined [[writable]] boolean if false, the property's [[value]] cannot be changed.
... false [[enumerable]] boolean if true, the property will be enumerated in for...in loops.
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Array.prototype.every() - JavaScript
otherwise, false.
...if such an element is found, the every method immediately returns false.
...if iscallable(callbackfn) is false, throw a typeerror exception.
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Array.prototype.some() - JavaScript
otherwise, false.
...otherwise, some() returns false.
... caution: calling this method on an empty array returns false for any condition!
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Iteration protocols - JavaScript
an object is an iterator when it implements a next() method with the following semantics: property value next() a zero-argument function that returns an object with at least the following two properties: done (boolean) has the value false if the iterator was able to produce the next value in the sequence.
...if a non-object value gets returned (such as false or undefined), a typeerror ("iterator.next() returned a non-object value") will be thrown.
...g the iteration protocols a string is an example of a built-in iterable object: let somestring = 'hi'; console.log(typeof somestring[symbol.iterator]); // "function" string's default iterator returns the string's code points one by one: let iterator = somestring[symbol.iterator](); console.log(iterator + ''); // "[object string iterator]" console.log(iterator.next()); // { value: "h", done: false } console.log(iterator.next()); // { value: "i", done: false } console.log(iterator.next()); // { value: undefined, done: true } some built-in constructs—such as the spread syntax—use the same iteration protocol under the hood: console.log([...somestring]); // ["h", "i"] you can redefine the iteration behavior by supplying our own @@iterator: // need to construct a string object explicitl...
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Logical NOT (!) - JavaScript
when used with non-boolean values, it returns false if its single operand can be converted to true; otherwise, returns true.
... syntax !expr description returns false if its single operand can be converted to true; otherwise, returns true.
...if a value can be converted to false, the value is so-called falsy.
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Index - XPath
18 boolean xslt, xslt_reference the boolean function evaluates an expression and returns true or false.
... 22 contains xslt, xslt_reference the contains function determines whether the first argument string contains the second argument string and returns boolean true or false.
... 26 element-available xslt, xslt_reference the element-available function determines if an element is available and returns true or false.
...And 4 more matches

Search Extension Tutorial (Draft) - Archive of obsolete content
var firstrun = false; // get the root user preference branch.
...var firstrun = false; // decide whether to select the search engine.
... var selectsearch = false; function startup(data, reason) { firstrun = reason == addon_install; // re-select the search engine if this is the first run // or we're being re-enabled.
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MMgc - Archive of obsolete content
// before sweeping we check for missing write barriers bool gc::incrementalvalidation = false; // check for missing write barriers at every alloc bool gc::incrementalvalidationpedantic = false; if you suspect you have missing write barriers, turn these switches on in a debug build.
...sometimes, this missing write barrier detection will turn up a false positive.
... if you can't find anything wrong with the code, it might just be a false positive.
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MenuItems - Archive of obsolete content
when the autocheck attribute is set to false, the checkbox state is not updated automatically, and you must write code to adjust the state yourself.
...<menuitem label="show toolbar" accesskey="t" type="checkbox" autocheck="false" oncommand="changetoolbarstate();"/> this version of the changetoolbarstate function changes the checked attribute itself.
... the autocheck attribute has been set to false on the menuitem so the checked attribute will not be updated automatically.
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Commands - Archive of obsolete content
if you return false, the command is not handled and command dispatcher will look for another controller.
... iscommandenabled (command) this method should return true if the command is enabled, or false if it is disabled.
...ler example" onload="init();" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> <script> function init() { var list = document.getelementbyid("thelist"); var listcontroller = { supportscommand : function(cmd){ return (cmd == "cmd_delete"); }, iscommandenabled : function(cmd){ if (cmd == "cmd_delete") return (list.selecteditem != null); return false; }, docommand : function(cmd){ list.removeitemat(list.selectedindex); }, onevent : function(evt){ } }; list.controllers.appendcontroller(listcontroller); } </script> <listbox id="thelist"> <listitem label="ocean"/> <listitem label="desert"/> <listitem label="jungle"/> <listitem label="swamp"/> </listbox> </window> the controller (listcontroller) implements t...
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Index - MDN Web Docs Glossary: Definitions of Web-related terms
for example, you can put a block of statements after an if (condition) block, indicating that the interpreter should run the code inside the block if the condition is true, or skip the whole block if the condition is false.
... 36 boolean boolean, codingscripting, glossary, javascript, programming languages, data types in computer science, a boolean is a logical data type that can have only the values true or false.
... 141 falsy codingscripting, glossary, javascript a falsy (sometimes written falsey) value is a value that is considered false when encountered in a boolean context.
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JavaScript basics - Learn web development
let myvariable = 10; boolean this is a true/false value.
... the words true and false are special keywords that don't need quote marks.
...it returns a true/false (boolean) result.
...And 3 more matches

Advanced Svelte: Reactivity, lifecycle, accessibility - Learn web development
you'll notice that the array is successfully updated every time you press the button (the todo objects' completed properties are toggled between true and false), but svelte is not aware of that.
... add the following import statement below the others inside todos.svelte: import newtodo from './newtodo.svelte' and update the addtodo() function like so: function addtodo(name) { todos = [...todos, { id: newtodoid, name, completed: false }] } addtodo() now receives the name of the new todo directly, so we no longer need the newtodoname variable to give it its value.
...update the first part of the newtodo.svelte <script> section (the first four lines) to look like this: <script> import { createeventdispatcher } from 'svelte' const dispatch = createeventdispatcher() export let autofocus = false let name = '' let nameel // reference to the name input dom node if (autofocus) nameel.focus() now go back to the todos component, and pass the autofocus prop into the <newtodo> component call, like so: <!-- newtodo --> <newtodo autofocus on:addtodo={e => addtodo(e.detail)} /> if you try your app out now, you'll see that the page is now blank, and in your ...
...And 3 more matches

mozbrowserselectionstatechanged
its properties are: canselectall: a boolean indicating whether the select all command can be issued (true) or not (false).
... cancut: a boolean indicating whether the cut command can be issued (true) or not (false).
... cancopy: a boolean indicating whether the copy command can be issued (true) or not (false).
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IPDL Tutorial
to initialize a union, simply assign a valid value to it, as follows: avariant = false; structs ipdl has built-in support for arbitrary collections of serializable data types.
... for a protocol pfoo managed by pmanager, that manages pmanagee, the methods are pmanager* pfoo::manager() const infallibletarray<pmanagee*> pfoo::managedpmanagee(); void pfoo::managedpmanagee(infallibletarray<pmanagee*>&); shutdown and error handling the c++ methods which implement ipdl messages return bool: true for success, and false for catastrophic failure.
... message implementations should return false from a message implementation if the data is corrupted or otherwise malformed.
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CustomizableUI.jsm
parameters awidgetid the widget id or dom node to check return value true if the widget can be removed from its area, false otherwise.
... return value true if this is possible, false if it is not.
... return value true if the widget is 'special', false otherwise.
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PKCS11 Implement
nss's interpretation of the ckf_login_required and ckf_user_pin_initialized flags cfk_login_required cfk_user_pin_initialized nss assumes that: false false this is a general access device.
... true false the device is uninitialized.
...the nss calls c_initpin to initialize the device and set the user pin; if these calls are successful, the key is generated and at that point the cfk_user_pin_initialized flag should change from false to true.
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JSVAL_TRUE
jsval constants that represent the javascript values true and false.
... syntax jsval_true jsval_false description jsval_true and jsval_false are jsval constants that represent the javascript boolean values, true and false.
... they are equivalent to boolean_to_jsval(true) and boolean_to_jsval(false), respectively.
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nsIClipboardCommands
return value true if an image is selected, false otherwise.
...return value true if an image is selected, false otherwise.
...return value true if a link is selected, false otherwise.
...And 3 more matches

nsIDOMXULElement
allowevents boolean true if the element's allowevents attribute is the string "true", otherwise false.
... removes the attribute if you set it to false.
... collapsed boolean true if the element's collapsed attribute is the string "true", otherwise false.
...And 3 more matches

nsIHttpChannel
this should be set to false, for example, if the application knows that the corresponding document is likely to be very large.
... return value returns true if the server sent the equivalent of a "cache-control: no-cache" response header, otherwise false.
...if avalue is empty and amerge is false, the header will be cleared.
...And 3 more matches

nsINavHistoryQueryOptions
by default, this is false.
...defaults to false.
...defaults to false.
...And 3 more matches

nsISHistoryListener
the listener can prevent any action (except adding a new session history entry) from happening by returning false from the corresponding callback method.
... return value true to allow the go back operation to proceed or false to cancel it.
... return value true to allow the go forward operation to proceed or false to cancel it.
...And 3 more matches

DevTools API - Firefox Developer Tools
default: false inverticonforlighttheme boolean, optional.
...default: false key string, optional.
...default: false inmenu boolean, optional.
...And 3 more matches

EventTarget.removeEventListener() - Web APIs
if this parameter is absent, a default value of false is assumed.
... for example, consider this call to addeventlistener(): element.addeventlistener("mousedown", handlemousedown, true); now consider each of these two calls to removeeventlistener(): element.removeeventlistener("mousedown", handlemousedown, false); // fails element.removeeventlistener("mousedown", handlemousedown, true); // succeeds the first call fails because the value of usecapture doesn't match.
... now consider this: element.addeventlistener("mousedown", handlemousedown, { passive: true }); here, we specify an options object in which passive is set to true, while the other options are left to the default value of false.
...And 3 more matches

KeyboardEvent() - Web APIs
"ctrlkey", optional and defaulting to false, of type boolean, that sets the value of keyboardevent.ctrlkey.
... "shiftkey", optional and defaulting to false, of type boolean, that sets the value of keyboardevent.shiftkey.
... "altkey", optional and defaulting to false, of type boolean, that sets the value of keyboardevent.altkey.
...And 3 more matches

MutationObserverInit - Web APIs
the default value is false.
...the default value is false.
...the default value is true if either of attributefilter or attributeoldvalue is specified, otherwise the default value is false.
...And 3 more matches

RTCPeerConnection.createOffer() - Web APIs
specify false to keep the same credentials and therefore not restart ice.
... the default is false.
...if this value is false, the remote peer will not be offered to send audio data, even if the local side will be sending audio data.
...And 3 more matches

Establishing a connection: The WebRTC perfect negotiation pattern - Web APIs
let makingoffer = false; pc.onnegotiationneeded = async () => { try { makingoffer = true; await pc.setlocaldescription(); signaler.send({ description: pc.localdescription }); } catch(err) { console.error(err); } finally { makingoffer = false; } }; note that setlocaldescription() without arguments automatically creates and sets the appropriate description based on the current signalingstate...
... once the offer has been created, set and sent (or an error occurs), makingoffer gets set back to false.
... let ignoreoffer = false; signaler.onmessage = async ({ data: { description, candidate }}) => { try { if (description) { const offercollision = (description.type == "offer") && (makingoffer || pc.signalingstate != "stable"); ignoreoffer = !polite && offercollision; if (ignoreoffer) { return; } await pc.setremotedescription(description); if ...
...And 3 more matches

Using XMLHttpRequest - Web APIs
however, if the lengthcomputable field is false, the total length is not known and will be zero.
...er(ofield.name) + "=" + ffilter(ofield.value) ); } } processstatus(this); } return function (oformelement) { if (!oformelement.action) { return; } new submitrequest(oformelement); }; })(); </script> </head> <body> <h1>sending forms with pure ajax</h1> <h2>using the get method</h2> <form action="register.php" method="get" onsubmit="ajaxsubmit(this); return false;"> <fieldset> <legend>registration example</legend> <p> first name: <input type="text" name="firstname" /><br /> last name: <input type="text" name="lastname" /> </p> <p> <input type="submit" value="submit" /> </p> </fieldset> </form> <h2>using the post method</h2> <h3>enctype: application/x-www-form-urlencoded (default)</h3> <form action="register.php"...
... method="post" onsubmit="ajaxsubmit(this); return false;"> <fieldset> <legend>registration example</legend> <p> first name: <input type="text" name="firstname" /><br /> last name: <input type="text" name="lastname" /> </p> <p> <input type="submit" value="submit" /> </p> </fieldset> </form> <h3>enctype: text/plain</h3> <form action="register.php" method="post" enctype="text/plain" onsubmit="ajaxsubmit(this); return false;"> <fieldset> <legend>registration example</legend> <p> your name: <input type="text" name="user" /> </p> <p> your message:<br /> <textarea name="message" cols="40" rows="8"></textarea> </p> <p> <input type="submit" value="submit" /> </p> </fieldset> </form> <h3>enctype: mult...
...And 3 more matches

Detecting CSS animation support - CSS: Cascading Style Sheets
testing for css animation support this code will check to see if css animation support is available: var animation = false, animationstring = 'animation', keyframeprefix = '', domprefixes = 'webkit moz o ms khtml'.split(' '), pfx = '', elem = document.createelement('div'); if( elem.style.animationname !== undefined ) { animation = true; } if( animation === false ) { for( var i = 0; i < domprefixes.length; i++ ) { if( elem.style[ domprefixes[i] + 'animationname' ] !== undefined ) { p...
...we assume that animation is not supported by setting animation to false.
... if the browser does not support non-prefixed animation and animation is still false, we iterate over all the possible prefixes, since all the major browsers are currently prefixing this property and changing its name to animationname instead.
...And 3 more matches

Border-radius generator - CSS: Cascading Style Sheets
rs[topic] = this; setvalue(topic, value); } var setvalue = function setvalue(topic, value, send_notify) { var slider = sliders[topic]; if (slider === undefined) return; if (value > slider.max) value = slider.max; if (value < slider.min) value = slider.min; slider.value = value; slider.node.setattribute('data-value', value); if (send_notify !== undefined && send_notify === false) { slider.input.value = value + slider.unit; return; } notify.call(slider); } var setmax = function setmax(topic, value) { var slider = sliders[topic]; if (slider === undefined) return; slider.max = value; setvalue(topic, slider.value); } var setmin = function setmin(topic, value) { var slider = sliders[topic]; if (slider === undefined) return; slider.min = ...
...; } return { init : init, setvalue : setvalue, subscribe : subscribe, unsubscribe : unsubscribe } })(); window.addeventlistener("load", function() { borderradius.init(); }); var borderradius = (function borderradius() { function getelembyid(id) { return document.getelementbyid(id); } /** * shadow dragging */ var previewmousetracking = (function drag() { var active = false; var lastx = 0; var lasty = 0; var subscribers = []; var init = function init(id) { var elem = getelembyid(id); elem.addeventlistener('mousedown', dragstart, false); document.addeventlistener('mouseup', dragend, false); } var dragstart = function dragstart(e) { if (e.button !== 0) return; active = true; lastx = e.clientx; lasty = e.clienty; document.adde...
...ventlistener('mousemove', mousedrag, false); } var dragend = function dragend(e) { if (e.button !== 0) return; if (active === true) { active = false; document.removeeventlistener('mousemove', mousedrag, false); } } var mousedrag = function mousedrag(e) { notify(e.clientx - lastx, e.clienty - lasty); lastx = e.clientx; lasty = e.clienty; } var subscribe = function subscribe(callback) { subscribers.push(callback); } var unsubscribe = function unsubscribe(callback) { var index = subscribers.indexof(callback); subscribers.splice(index, 1); } var notify = function notify(deltax, deltay) { for (var i in subscribers) subscribers[i](deltax, deltay); } return { init : init, subscribe : subscribe, unsubscribe : unsubscr...
...And 3 more matches

Array.prototype.includes() - JavaScript
the includes() method determines whether an array includes a certain value among its entries, returning true or false as appropriate.
...(that is, -0 is considered to be equal to both 0 and +0), but false is not considered to be the same as 0.
... examples [1, 2, 3].includes(2) // true [1, 2, 3].includes(4) // false [1, 2, 3].includes(3, 3) // false [1, 2, 3].includes(3, -1) // true [1, 2, nan].includes(nan) // true fromindex is greater than or equal to the array length if fromindex is greater than or equal to the length of the array, false is returned.
...And 3 more matches

Array.isArray() - JavaScript
array.isarray([1, 2, 3]); // true array.isarray({foo: 123}); // false array.isarray('foobar'); // false array.isarray(undefined); // false syntax array.isarray(value) parameters value the value to be checked.
... return value true if the value is an array; otherwise, false.
... description if the value is an array, true is returned; otherwise, false is.
...And 3 more matches

Object.isSealed() - JavaScript
description returns true if the object is sealed, otherwise false.
...var empty = {}; object.issealed(empty); // === false // if you make an empty object non-extensible, // it is vacuously sealed.
...var hasprop = { fee: 'fie foe fum' }; object.preventextensions(hasprop); object.issealed(hasprop); // === false // but make them all non-configurable // and the object becomes sealed.
...And 3 more matches

Equality (==) - JavaScript
if one of the operands is boolean, convert the boolean operand to 1 if it is true and +0 if it is false.
...if either operand is nan, return false.
... boolean: return true only if operands are both true or both false.
...And 3 more matches

HTML to DOM - Archive of obsolete content
lstring){ var html = document.implementation.createdocument("http://www.w3.org/1999/xhtml", "html", null), body = document.createelementns("http://www.w3.org/1999/xhtml", "body"); html.documentelement.appendchild(body); body.appendchild(components.classes["@mozilla.org/feed-unescapehtml;1"] .getservice(components.interfaces.nsiscriptableunescapehtml) .parsefragment(ahtmlstring, false, null, body)); return body; } it works by creating a content-level (this is safer than chrome-level) <div> in the current page, then parsing the html fragment and attaching that fragment to the <div>.
...for that matter, we're going to load our html document first: var request = xmlhttprequest(); request.open("get", "http://example.org/file.html", false); request.send(null); our next step is to create the document object that will represent the dom into which we'll insert our newly-retrieved html: var doc = document.implementation.createhtmldocument("example"); doc.documentelement.innerhtml = request.responsetext; after this any manipulation that we might want to do will be something as simple as the following: doc.body.textcontent = "this...
...// iframe (or browser on older firefox) frame.setattribute("id", "sample-frame"); frame.setattribute("name", "sample-frame"); frame.setattribute("type", "content"); frame.setattribute("collapsed", "true"); document.getelementbyid("main-window").appendchild(frame); // or // document.documentelement.appendchild(frame); // set restrictions as needed frame.webnavigation.allowauth = false; frame.webnavigation.allowimages = false; frame.webnavigation.allowjavascript = false; frame.webnavigation.allowmetaredirects = true; frame.webnavigation.allowplugins = false; frame.webnavigation.allowsubframes = false; // listen for load frame.addeventlistener("load", function (event) { // the document of the html in the dom var doc = event.originaltarget; // skip blank ...
...And 2 more matches

Preferences - Archive of obsolete content
to add a default value for a preference, you should add a line like this to your default preferences file: pref("extensions.extensionname.preferencename", false); how to install an extension's defaults files for mozilla suite (not firefox and thunderbird), copy them to (appdir)/defaults/pref in your install script.
... this.branch.addobserver("", this, false); }, unregister: function() { this.branch.removeobserver("", this); }, observe: function(asubject, atopic, adata) { // asubject is the nsiprefbranch we're observing (after appropriate qi) // adata is the name of the pref that's been changed (relative to asubject) switch (adata) { case "pref1": // extensions.myextension.pref1 was changed break; ...
... */ preflistener.prototype.register = function(trigger) { this._branch.addobserver('', this, false); if (trigger) { let that = this; this._branch.getchildlist('', {}).
...And 2 more matches

Chapter 4: Using XPCOM—Implementing advanced processes - Archive of obsolete content
listing 7: check that file exists, delete it, and create it file.initwithpath('c:\\temp\\temp.txt'); if (file.exists()) file.remove(false); file.create(file.normal_file_type, 0666); the first parameter of the nsilocalfile.create() method gives the type of file to create.
... listing 13: reading the contents of a binary file file.initwithpath('c:\\temp\\temp.txt'); var filestream = components.classes['@mozilla.org/network/file-input-stream;1'] .createinstance(components.interfaces.nsifileinputstream); filestream.init(file, 1, 0, false); var binarystream = components.classes['@mozilla.org/binaryinputstream;1'] .createinstance(components.interfaces.nsibinaryinputstream); binarystream.setinputstream(filestream); var array = binarystream.readbytearray(filestream.available()); binarystream.close(); filestream.close(); alert(array.map( function(aitem) {return aitem.tostring(16); } ).join(' ').toupper...
... listing 14: writing a binary file var array = [88, 85, 76]; file.initwithpath('c:\\temp\\temp.txt'); if (file.exists()) file.remove(true); file.create(file.normal_file_type, 0666); var filestream = components.classes['@mozilla.org/network/file-output-stream;1'] .createinstance(components.interfaces.nsifileoutputstream); filestream.init(file, 2, 0x200, false); var binarystream = components.classes['@mozilla.org/binaryoutputstream;1'] .createinstance(components.interfaces.nsibinaryoutputstream); binarystream.setoutputstream(filestream); binarystream.writebytearray(array , array.length); binarystream.close(); filestream.close(); text file i/o text files are read the same way streams are.
...And 2 more matches

Special Condition Tests - Archive of obsolete content
the iscontainer attribute should be set to true if you only want to match containers, and false if you only want to match non-containers.
...we could also have left the rules in the original order and set the iscontainer on the first rule to false.
...note that leaving out the iscontainer attribute is not the same as setting it to either true or false.
...And 2 more matches

textbox (Toolkit autocomplete) - Archive of obsolete content
if set to false or omitted, the value must be selected from the list.
...if false, the default, autocomplete is enabled.
...do not set the attribute to true, as this will suggest you can set it to false to enable the element again, which is not the case.
...And 2 more matches

menuitem - Archive of obsolete content
if this attribute is false, the checked state must be adjusted manually.
...a workaround is to set the autocheck attribute to false, then programmatically set the checked attribute when the user selects the item, and set it to false instead of removing the attribute (i.e.
... do menuitem.setattribute("checked", "false") instead of menuitem.removeattribute("checked")) when the user unchecks the menuitem, as a value of false will both correctly hide the checkmark and persist its hidden state.
...And 2 more matches

prefwindow - Archive of obsolete content
this one can be safely omitted in xulrunner-based applications but you can override the default behavior (true for mac os x and false for other platforms) setting it.
... the default setting of browser.preferences.instantapply currently is true on linux and mac os and false on windows (which however might or might not change soon, see bug 738797 and bug 1037225).
...returning false doesn't currently prevent the dialog from closing, but does prevent saving (bug 474527).
...And 2 more matches

Common causes of memory leaks in extensions - Extensions
consider the following example code that could be part of your browser.xul overlay: gbrowser.addeventlistener("domcontentloaded", function(evt) { var contentdoc = evt.originaltarget; var i = 0; // refresh the title once each second setinterval(function() { contentdoc.title = ++i; }, 1000); }, false); one would normally expect that the interval (or timer) would be destroyed as soon as the document unloads, in the same way that event listeners are automatically destroyed.
... // unload(function() window.removeeventlistener("leaky", leakref, false), window); // this is the right way to do it remove the listener.
..."private" : "normal"); } }; services.obs.addobserver(myobserver, "private-browsing", /* ownsweak */ false); the ownsweak = false parameter causes the observer service to use a strong reference to the observer object, which will cause it to hold onto the whole window.
...And 2 more matches

Paddle and keyboard controls - Game development
add these lines somewhere near the rest of your variables: var rightpressed = false; var leftpressed = false; the default value for both is false because at the beginning the control buttons are not pressed.
...add the following lines just above the setinterval() line at the bottom of your javascript: document.addeventlistener("keydown", keydownhandler, false); document.addeventlistener("keyup", keyuphandler, false); when the keydown event is fired on any of the keys on your keyboard (when they are pressed), the keydownhandler() function will be executed.
...add these to your code now, below the addeventlistener() lines: function keydownhandler(e) { if(e.key == "right" || e.key == "arrowright") { rightpressed = true; } else if(e.key == "left" || e.key == "arrowleft") { leftpressed = true; } } function keyuphandler(e) { if(e.key == "right" || e.key == "arrowright") { rightpressed = false; } else if(e.key == "left" || e.key == "arrowleft") { leftpressed = false; } } when we press a key down, this information is stored in a variable.
...And 2 more matches

TypeScript support in Svelte - Learn web development
now from todos.svelte, we will instantiate a todo component with a literal object as its parameter before the call to the moreactions component, like this: <hr /> <todo todo={ { name: 'a new task with no id!', completed: false } } /> <!-- moreactions --> <moreactions {todos} add the lang='ts' to the <script> tag of the todos.svelte component, so that it knows to use the type checking we have specified.
...math.max(...todos.map(t => t.id)) + 1 : 1 function addtodo(name: string) { todos = [...todos, { id: newtodoid, name, completed: false }] $alert = `todo '${name}' has been added` } function removetodo(todo: todotype) { todos = todos.filter(t => t.id !== todo.id) todosstatus.focus() // give focus to status heading $alert = `todo '${todo.name}' has been deleted` } function updatetodo(todo: todotype) { const i = todos.findindex(t => t.id === todo.id) if (todos[i].name !== todo.name) ...
...set its type to htmlelement like this: let nameel: htmlelement // reference to the name input dom node last for this file, we need to specify the correct type for our autofocus variable; update its definition like this: export let autofocus: boolean = false todo.svelte now the only warnings that npm run validate emits are triggered by calling the todo.svelte component; let's fix them.
...And 2 more matches

Dynamic behavior in Svelte: working with variables and props - Learn web development
create a <script> section at the top of src/components/todos.svelte and give it some content, as follows: <script> let todos = [ { id: 1, name: 'create a svelte starter app', completed: true }, { id: 2, name: 'create your first component', completed: true }, { id: 3, name: 'complete the rest of the tutorial', completed: false } ] let totaltodos = todos.length let completedtodos = todos.filter(todo => todo.completed).length </script> now let's do something with that information.
...update src/app.svelte as follows: <script> import todos from './components/todos.svelte' let todos = [ { id: 1, name: 'create a svelte starter app', completed: true }, { id: 2, name: 'create your first component', completed: true }, { id: 3, name: 'complete the rest of the tutorial', completed: false } ] </script> <todos todos={todos} /> when the attribute and the variable have the same name, svelte allows you to just specify the variable as a handy shortcut, so we can rewrite our last line like this.
...add this to the bottom of your <script> block inside src/components/todo.svelte: function addtodo() { todos.push({ id: 999, name: newtodoname, completed: false }) newtodoname = '' } note: for the moment we are just assigning the same id to every todo, but don't worry, we will fix that soon.
...And 2 more matches

Rendering a list of Vue components - Learn web development
export default { name: 'app', components: { todoitem }, data() { return { todoitems: [ { label: 'learn vue', done: false }, { label: 'create a vue project with the cli', done: true }, { label: 'have fun', done: true }, { label: 'create a to-do list', done: false } ] }; } }; now that we have a list of items, we can use the v-for directive to display them.
... your app.vue <script> element contents should now look like this: import todoitem from './components/todoitem.vue'; import uniqueid from 'lodash.uniqueid' export default { name: 'app', components: { todoitem }, data() { return { todoitems: [ { id: uniqueid('todo-'), label: 'learn vue', done: false }, { id: uniqueid('todo-'), label: 'create a vue project with the cli', done: true }, { id: uniqueid('todo-'), label: 'have fun', done: true }, { id: uniqueid('todo-'), label: 'create a to-do list', done: false } ] }; } }; now, add the v-for directive and key attribute to the <li> element in your app.vue template, like so: <ul> <li v-for="item in tod...
...in addition, we want their checked status to reflect their done properties, not always be set to done="false".
...And 2 more matches

Communicating with frame scripts
le below sends a message named "my-e10s-extension-message", with a data payload containing details and tag properties, and exposes the event.target object as a cpow: // frame script addeventlistener("click", function (event) { sendasyncmessage("my-addon@me.org:my-e10s-extension-message", { details : "they clicked", tag : event.target.tagname }, { target : event.target }); }, false); to receive messages from content, a chrome script needs to add a message listener using the message manager's addmessagelistener() api.
...y-e10s-extension-message", listener); function listener(message) { console.log(message.name); console.log(message.sync); console.log(message.data); console.log(message.target); console.log(message.objects); } so combining this message listener with the message above will give console output somewhat like this, when the user clicks a <div>: "my-addon@me.org:my-e10s-extension-message" false object { details: "they clicked", tag: "div" } <xul:browser anonid="initialbrowser" ...
...value of sendsyncmessage() is an array of all the values returned from every listener, even if it only contains a single value: // frame script addeventlistener("click", function (event) { var results = sendsyncmessage("my-addon@me.org:my-e10s-extension-message", { details : "they clicked", tag : event.target.tagname }); content.console.log(results[0]); // "value from chrome" }, false); like arguments, return values from sendsyncmessage() must be json-serializable, so chrome can't return functions.
...And 2 more matches

Midas
contentreadonly this command will make the editor readonly(true)or editable(false).
... insertbronreturn true/false selects whether pressing return inside a paragraph creates another paragraph or just inserts a <br> tag.
...an example of the differences is that the "bold" command will generate <b> if the stylewithcss command is false and generate css style attribute if the stylewithcss command is true.
...And 2 more matches

Enc Dec MAC Output Public Key as CSR
citem_freeitem(data, pr_true); } return rv; } /* * generate a symmetric key */ pk11symkey * generatesymkey(pk11slotinfo *slot, ck_mechanism_type mechanism, int keysize, secitem *keyid, secupwdata *pwdata) { secstatus rv; pk11symkey *key; /* generate the symmetric key */ key = pk11_tokenkeygen(slot, mechanism, null, keysize, keyid, pr_false, pwdata); if (!key) { pr_fprintf(pr_stderr, "symmetric key generation failed \n"); } return key; } /* * macinit */ secstatus macinit(pk11context *ctx) { secstatus rv = pk11_digestbegin(ctx); if (rv != secsuccess) { pr_fprintf(pr_stderr, "compute mac failed : pk11_digestbegin()\n"); } return rv; } /* * macupdate */ secstatus macupdate(pk11context...
...asn1_get(cert_certificaterequesttemplate), &signeddata.data); if (rv) { rv = secfailure; goto cleanup; } rv = cert_verifysigneddatawithpublickeyinfo(&signeddata, &certreq->subjectpublickeyinfo, null /* wincx */); publickey = seckey_extractpublickey(&certreq->subjectpublickeyinfo); cleanup: if (reqder.data) { secitem_freeitem(&reqder, pr_false); } if (arena) { port_freearena(arena, pr_false); } return publickey; } /* * get the private key corresponding to public key */ seckeyprivatekey * getrsaprivatekey(pk11slotinfo *slot, secupwdata *pwdata, seckeypublickey *pubkey) { seckeyprivatekey *privkey = null; secitem *cka_id; if (slot...
...printf(pr_stderr, "unable to make certificate request\n"); rv = secfailure; goto cleanup; } arena = port_newarena(der_default_chunksize); if (!arena) { fprintf(stderr, "out of memory"); rv = secfailure; goto cleanup; } exthandle = cert_startcertificaterequestattributes(cr); if (exthandle == null) { port_freearena (arena, pr_false); rv = secfailure; goto cleanup; } cert_finishextensions(exthandle); cert_finishcertificaterequestattributes(cr); /* der encode the request */ encoding = sec_asn1encodeitem(arena, null, cr, sec_asn1_get(cert_certificaterequesttemplate)); if (encoding == null) { pr_fprintf(pr_stderr, "der encoding of request failed...
...And 2 more matches

JSDeletePropertyOp
this callback may veto the ongoing property operation by optionally reporting an error or raising an exception and then returning false.
... if an error occurred, return false as per normal jsapi error practice.
... if no error occurred, but the deletion attempt wasn't allowed (perhaps because the property was non-configurable), set *succeeded to false and return true.
...And 2 more matches

JS_DeleteProperty2
on success, *succeeded receives false if the property was not deleted because it is permanent and true otherwise.
... description js_deleteproperty2 removes a specified property, name, from an object, obj, and stores true or false in *succeeded.
... if obj has the specified property but it is permanent, then *succeeded receives false.
...And 2 more matches

Starting WebLock
* pr_false if there are no more elements in the enumerator.
...* false - the provider will be asked for this prop * each time it is requested.
...this boolean value will be used later to determine if we should be denying url requests: /* void lock (); */ ns_imethodimp weblock::lock() { mlocked = pr_true; return ns_ok; } /* void unlock (); */ ns_imethodimp weblock::unlock() { mlocked = pr_false; return ns_ok; } addsite for addsite, we add a new node to our linked list.
...And 2 more matches

Using XPCOM Components
ns_get_iid(nsicookiemanager), getter_addrefs(cookiemanager)); if (ns_failed(rv)) return -1; pruint32 len; deletedcookies->getlength(&len); for (int c=0; c<len; c++) cookiemanager->remove(deletedcookies[c].host, deletedcookies[c].name, deletedcookies[c].path, pr_false); xxx: in the original document, there were only the first three parameters to the |remove| call.
... i added |pr_false| as a fourth parameter because the interface seems to require it: http://lxr.mozilla.org/mozilla/source/netwerk/cookie/public/nsicookiemanager.idl#64 this problem also appears in the javascript version below, and i've added |false| as a fourth parameter there as well.
... managing cookies from javascript var cmgr = components.classes["@mozilla.org/cookiemanager;1"] .getservice(); cmgr = cmgr.queryinterface(components.interfaces.nsicookiemanager); function loadcookies() { // load cookies into a table var enumerator = cmgr.enumerator; var count = 0; var showpolicyfield = false; while (enumerator.hasmoreelements()) { var nextcookie = enumerator.getnext(); nextcookie = nextcookie.queryinterface(components.interfaces.nsicookie); /* ....
...And 2 more matches

Index
24 components.issuccesscode xpcom, xpcom:language bindings, xpconnect determines whether a given xpcom return code (that is, an nsresult value) indicates the success or failure of an operation, returning true or false respectively.
... 141 ns ensure success xpcom, xpcom_macros macro 142 ns ensure true xpcom, xpcom_macros macro 143 ns_abort_if_false this was removed in bug 1127201 144 ns_addref xpcom, xpcom_macros macro 145 ns_assertion xpcom, xpcom_macros macro 146 ns_ensure_arg_pointer xpcom, xpcom_macros macro 147 ns_error xpcom, xpcom_macros throws a assertion (ns_assertion) with the text "error: (error text)", so writes this text to console (s...
...when a method doesn't implement this method it must return s_false.
...And 2 more matches

Components.utils.cloneInto
if omitted the default value is false.
...if omitted the default value is false.
...s it a property of the content window global: // add-on script var addonscriptobject = {"greeting" : "hello from add-on"}; contentwindow.addonscriptobject = cloneinto(addonscriptobject, contentwindow); scripts running in the page can now access the object: // page script button.addeventlistener("click", function() { console.log(window.addonscriptobject.greeting); // "hello from add-on" }, false); of course, you don't have to assign the clone to the window itself: you can assign it to some other object in the target scope: contentwindow.foo.addonscriptobject = cloneinto(addonscriptobject, contentwindow); you can also pass it into a function defined in the page script.
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Components.utils.exportFunction
boolean, defaulting to false.
...boolean, defaulting to false.
...{ user.name = "bill"; } exportfunction(changemyname, contentwindow, { defineas: "changemyname" }); // less-privileged scope: for example, a page script var user = {name: "jim"}; var test = document.getelementbyid("test"); test.addeventlistener("click", function() { console.log(user.name); // "jim" window.changemyname(user); console.log(user.name); // "bill" }, false); note that this is subject to the normal rules of xrays: for example, an expando property added to a dom node will not be visible in the original object.
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mozIStorageConnection
this will be false if the connection failed to open, or it has been closed.
...otherwise returns false.
...this is false by default.
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nsIAppShell
when the number of calls that pass pr_true is subtracted from the number of calls that pass pr_false is greater than 0, performance is given precedence over preventing event starvation.
... void favorperformancehint( in boolean favorperfoverstarvation, in unsigned long starvationdelay ); parameters favorperfoverstarvation true to favor event performance over event starvation, false to favor event starvation over event performance.
... starvationdelay is only used when favorperfoverstarvation is pr_false.
...And 2 more matches

nsIDOMNSHTMLDocument
return value true if the command was recognized, false otherwise.
... return value returns true if the command is supported and enabled, false otherwise.
... return value for stateful commands, returns true if the command is in an indeterminate state, false otherwise.
...And 2 more matches

nsINavBookmarksService
if ownsweak is false, the bookmark service will keep an owning reference to the observer.
...the default for all folders is false.
... return value returns true if the folder is marked as read-only, otherwise returns false.
...And 2 more matches

nsIWebBrowserFind
default is false.
...default is false (search forward).
...default is false.
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Styling the Folder Pane
hasunreadmessages-true afolder.getnumunread(false) > 0 indicates that the folder (but not subfolders) has unread messages.
... issecure-{true, false} afolder.server.issecure indicates whether or not the connection to the server will be secure.
... newmessages-true afolder.hasnewmessages subfoldershaveunreadmessages-true afolder.getnumunread(true) > afolder.getnumunread(false) indicates whether or not subfolders have unread messages.
...And 2 more matches

Drawing and Event Handling - Plugins
an embedded plug-in can set the pluginprinted field in its printinfo parameter to false (the default).
... to specify that a plug-in is windowless, use npn_setvalue with nppvpluginwindowbool as the value of variable and false as the value of value.
... nperror result = npn_setvalue(instance, nppvpluginwindowbool, (void*)false); } invalidating the drawing area before it can repaint or refresh part of its drawing area, a windowless plug-in must first invalidate the area with either of these browser methods: npn_invalidaterect or npn_invalidateregion.
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Debugger - Firefox Developer Tools
it is an accessor property with a getter and setter: assigning to it enables or disables this debugger instance; reading it produces true if the instance is enabled, or false otherwise.
...setting this to false inhibits the ahead-of-time asm.js compiler and forces asm.js code to run as normal javascript.
...it is initially false in a freshly created debugger instance.
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AudioWorkletProcessor.process - Web APIs
returning true forces the web audio api to keep the node alive, while returning false allows the browser to terminate the node if it is neither generating new audio data nor receiving data through its inputs that it is processing.
...the method should return false as soon as it's known that it will no longer produce an output.
... for example, take the audiobuffersourcenode — the processor behind such a node should return true from the process method while the buffer is playing, and start returning false when the buffer playing has ended (there's no way to call play on the same audiobuffersourcenode again).
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Cache.delete() - Web APIs
if no cache entry is found, it resolves to false.
...it defaults to false.
... ignoremethod: a boolean that, when set to true, prevents matching operations from validating the request http method (normally only get and head are allowed.) it defaults to false.
...And 2 more matches

Document.execCommand() - Web APIs
syntax document.execcommand(acommandname, ashowdefaultui, avalueargument) return value a boolean that is false if the command is unsupported or disabled.
...this requires a boolean true/false as the value argument.
...requires a boolean true/false as a value argument.
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Element.classList - Web APIs
null : n} return nullcheck(this[i]); }; if (!domtokenlistproto.toggle || testclass.toggle("a",0)!==false) domtokenlistproto.toggle=function(val){ if (arguments.length > 1) return (this[arguments[1] ?
... "add" : "remove"](val), !!arguments[1]); var oldvalue = this.value; return (this.remove(oldvalue), oldvalue === this.value && (this.add(val), true) /*|| false*/); }; if (!domtokenlistproto.replace || typeof testclass.replace("a", "b") !== "boolean") domtokenlistproto.replace = function(oldtoken, newtoken){ checkifvalidclasslistentry("replace", oldtoken), checkifvalidclasslistentry("replace", newtoken); var oldvalue = this.value; return (this.remove(oldtoken), this.value !== oldvalue && (this.add(newtoken), true)); }; if (!domtokenlistproto.contains) domtokenlistproto.contains = function(value){ for (var i=0,len=this.length; i !== len; ++i) if (this[i] === value) return true; return false; }; ...
...{value: [nextindex, that[nextindex++]], done: false} : {done: true}; }}; }; if (!domtokenlistproto.values) domtokenlistproto.values = function(){ var nextindex = 0, that = this; return {next: function() { return nextindex<that.length ?
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FileSystemFlags.create - Web APIs
option values file/directory condition result create exclusive false n/a[1] path exists and matches the desired type (depending on whether the function called is getfile() or getdirectory() the successcallback is called with a filesystemfileentry if getfile() was called or a filesystemdirectoryentry if getdirectory() was called.
... false n/a[1] path exists but doesn't match the desired type the errorcallback is called with an appropriate error code (if the callback was provided).
... true false path exists the existing file or directory is removed and replaced with a new one, then the successcallback is called with a filesystemfileentry or a filesystemdirectoryentry, as appropriate.
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FileSystemFlags.exclusive - Web APIs
option values file/directory condition result create exclusive false n/a[1] path exists and matches the desired type (depending on whether the function called is getfile() or getdirectory() the successcallback is called with a filesystemfileentry if getfile() was called or a filesystemdirectoryentry if getdirectory() was called.
... false n/a[1] path exists but doesn't match the desired type the errorcallback is called with an appropriate error code (if the callback was provided).
... true false path exists the existing file or directory is removed and replaced with a new one, then the successcallback is called with a filesystemfileentry or a filesystemdirectoryentry, as appropriate.
...And 2 more matches

HTMLInputElement - Web APIs
this is the empty string if the control is not a candidate for constraint validation (willvalidate is false), or it satisfies its constraints.
...it is false if any conditions bar it from constraint validation, including: its type is hidden, reset, or button; it has a <datalist> ancestor; its disabled property is true.
...does not affect the value of the checked attribute, and clicking the checkbox will set the value to false.
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HTMLTextAreaElement - Web APIs
this is the empty string if the control is not a candidate for constraint validation (willvalidate is false), or it satisfies its constraints.
...false if any conditions bar it from constraint validation, including its readonly or disabled property is true.
... checkvalidity() returns false if the element is a candidate for constraint validation, and it does not satisfy its constraints.
...And 2 more matches

Drag Operations - Web APIs
if this attribute were omitted or set to "false", the element would not be dragged, and instead the text would be selected.
...however, for these last two, the default value is true, so you would only use the draggable attribute with a value of false to disable dragging of these elements.
...you can do this either by returning false from attribute-defined event listeners, or by calling the event's preventdefault() method.
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Using IndexedDB - Web APIs
objectstore.createindex("name", "name", { unique: false }); // create an index to search customers by email.
...yrange.lowerbound("bill"); // match anything past "bill", but don't include "bill" var lowerboundopenkeyrange = idbkeyrange.lowerbound("bill", true); // match anything up to, but not including, "donna" var upperboundopenkeyrange = idbkeyrange.upperbound("donna", true); // match anything between "bill" and "donna", but not including "donna" var boundkeyrange = idbkeyrange.bound("bill", "donna", false, true); // to use one of the key ranges, pass it in as the first argument of opencursor()/openkeycursor() index.opencursor(boundkeyrange).onsuccess = function(event) { var cursor = event.target.result; if (cursor) { // do something with the matches.
... idbindex has also had new properties added to it to specify if it has a locale specified, and what it is: locale (returns the locale if any, or null if none is specified) and isautolocale (returns true if the index was created with an auto locale, meaning that the platform's default locale is used, false otherwise.) note: this feature is currently hidden behind a flag — to enable it and experiment, go to about:config and enable dom.indexeddb.experimental.
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MediaStreamTrack - Web APIs
mediastreamtrack.enabled a boolean whose value of true if the track is enabled, that is allowed to render the media source stream; or false if it is disabled, that is not rendering the media source stream but silence and blackness.
... note: you can implement standard "mute" functionality by setting enabled to false.
... note: you can implement standard "mute" functionality by setting enabled to false, and unmute the media by setting it back to true again.
...And 2 more matches

SpeechRecognition.interimResults - Web APIs
the interimresults property of the speechrecognition interface controls whether interim results should be returned (true) or not (false.) interim results are results that are not yet final (e.g.
... the speechrecognitionresult.isfinal property is false.) the default value for interimresults is false.
... syntax var myinterimresult = myspeechrecognition.interimresults; myspeechrecognition.interimresults = false; value a boolean representing the state of the current speechrecognition's interim results.
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WebGL constants - Web APIs
returns false if the shader was not compiled.
...returns true if it was, false otherwise.
...returns false if there were errors.
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Controlling multiple parameters with ConstantSourceNode - Web APIs
let context = null; let playbutton = null; let volumecontrol = null; let oscnode1 = null; let oscnode2 = null; let oscnode3 = null; let constantnode = null; let gainnode1 = null; let gainnode2 = null; let gainnode3 = null; let playing = false; these variables are: context the audiocontext in which all the audio nodes live.
... function setup() { context = new (window.audiocontext || window.webkitaudiocontext)(); playbutton = document.queryselector("#playbutton"); volumecontrol = document.queryselector("#volumecontrol"); playbutton.addeventlistener("click", toggleplay, false); volumecontrol.addeventlistener("input", changevolume, false); gainnode1 = context.creategain(); gainnode1.gain.value = 0.5; gainnode2 = context.creategain(); gainnode3 = context.creategain(); gainnode2.gain.value = gainnode1.gain.value; gainnode3.gain.value = gainnode1.gain.value; volumecontrol.value = gainnode1.gain.value; constantnode = context.createconstantsource(); c...
...onstantnode.connect(gainnode2.gain); constantnode.connect(gainnode3.gain); constantnode.start(); gainnode1.connect(context.destination); gainnode2.connect(context.destination); gainnode3.connect(context.destination); } window.addeventlistener("load", setup, false); first, we get access to the window's audiocontext, stashing the reference in context.
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Using the Web Audio API - Web APIs
we have a play button that changes to a pause button when the track is playing: <button data-playing="false" role="switch" aria-checked="false"> <span>play/pause</span> </button> before we can play our track we need to connect our audio graph from the audio source/input node to the destination.
... // select our play button const playbutton = document.queryselector('button'); playbutton.addeventlistener('click', function() { // check if context is in suspended state (autoplay policy) if (audiocontext.state === 'suspended') { audiocontext.resume(); } // play or pause track depending on state if (this.dataset.playing === 'false') { audioelement.play(); this.dataset.playing = 'true'; } else if (this.dataset.playing === 'true') { audioelement.pause(); this.dataset.playing = 'false'; } }, false); we also need to take into account what to do when the track finishes playing.
... our htmlmediaelement fires an ended event once it's finished playing, so we can listen for that and run code accordingly: audioelement.addeventlistener('ended', () => { playbutton.dataset.playing = 'false'; }, false); modifying sound let's delve into some basic modification nodes, to change the sound that we have.
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Window.open() - Web APIs
*/ }; } </script> (...) <p><a href="http://www.spreadfirefox.com/" target="promotefirefoxwindowname" onclick="openffpromotionpopup(); return false;" title="this link will create a new window or will re-use an already opened one" >promote firefox adoption</a></p> the above code solves a few usability problems related to links opening secondary window.
... the purpose of the return false in the code is to cancel default action of the link: if the onclick event handler is executed, then there is no need to execute the default action of the link.
...pup(url, windowname) { if(windowobjectreference == null || windowobjectreference.closed) { windowobjectreference = window.open(url, windowname, "resizable,scrollbars,status"); } else { windowobjectreference.focus(); }; } </script> (...) <p><a href="http://www.spreadfirefox.com/" target="promotefirefoxwindow" onclick="openrequestedpopup(this.href, this.target); return false;" title="this link will create a new window or will re-use an already opened one" >promote firefox adoption</a></p> you can also make such function able to open only 1 secondary window and to reuse such single secondary window for other links in this manner: <script type="text/javascript"> var windowobjectreference = null; // global variable var previousurl; /* global variable that will store...
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ARIA: tab role - Accessibility
when working with elements with the tab role, when they are selected or active, they should have their aria-selected attribute set to true, otherwise it should be set to false.
... when a tab is selected or active, its controlled tabpanel should have its aria-expanded and hidden attributes set to true, otherwise they should be set to false.
... <div class="tabs"> <div role="tablist" aria-label="sample tabs"> <button role="tab" aria-selected="true" aria-controls="panel-1" id="tab-1" tabindex="0"> first tab </button> <button role="tab" aria-selected="false" aria-controls="panel-2" id="tab-2" tabindex="-1"> second tab </button> <button role="tab" aria-selected="false" aria-controls="panel-3" id="tab-3" tabindex="-1"> third tab </button> </div> <div id="panel-1" role="tabpanel" tabindex="0" aria-labelledby="tab-1"> <p>content for the first panel</p> </div> <div id="panel-2" role="tabpanel" tabindex=...
...And 2 more matches

ARIA: checkbox role - Accessibility
<span role="checkbox" aria-checked="false" tabindex="0" aria-labelledby="chk1-label"> </span> <label id="chk1-label">remember my preferences</label> the first rule of aria is if a native html element or attribute has the semantics and behavior you require, use it instead of re-purposing an element and adding aria.
...similarly, an element with role="checkbox" can expose three states through the aria-checked attribute: true, false, or mixed.
...this attribute has one of three possible values: true the checkbox is checked false the checkbox is not checked mixed the checkbox is partially checked, or indeterminate tabindex="0" used to make it focusable so the assistive technology user can tab to it and start reading right away.
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ARIA: listbox role - Accessibility
all options that are not selected have aria-selected set to false.
...if set to true, every selectable option should have an aria-selected attribute included and set to true or false.
... if false or omitted, only the currently selected option, if any option is selected, needs the aria-selected attribute, and it must be set to true.
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Making content editable - Developer guides
for example, to use <p> elements: document.execcommand("defaultparagraphseparator", false, "p"); additionally, firefox supports the non-standard argument, br, for defaultparagraphseparator since firefox 55.
...you can use the older firefox behavior with this line: document.execcommand("defaultparagraphseparator", false, "br"); security for security reasons, firefox doesn't let javascript code use clipboard related features (copy, paste, etc.) by default.
...imple but complete rich text editor <!doctype html> <html> <head> <title>rich text editor</title> <script type="text/javascript"> var odoc, sdeftxt; function initdoc() { odoc = document.getelementbyid("textbox"); sdeftxt = odoc.innerhtml; if (document.compform.switchmode.checked) { setdocmode(true); } } function formatdoc(scmd, svalue) { if (validatemode()) { document.execcommand(scmd, false, svalue); odoc.focus(); } } function validatemode() { if (!document.compform.switchmode.checked) { return true ; } alert("uncheck \"show html\"."); odoc.focus(); return false; } function setdocmode(btosource) { var ocontent; if (btosource) { ocontent = document.createtextnode(odoc.innerhtml); odoc.innerhtml = ""; var opre = document.createelement("pre"); odoc.content...
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<input type="button"> - HTML: Hypertext Markup Language
disabling and enabling a button to disable a button, simply specify the disabled global attribute on it, like so: <input type="button" value="disable me" disabled> you can enable and disable buttons at run time by simply setting disabled to true or false.
... hidden code 1 <input type="button" value="enabled"> const button = document.queryselector('input'); button.addeventlistener('click', disablebutton); function disablebutton() { button.disabled = true; button.value = 'disabled'; window.settimeout(function() { button.disabled = false; button.value = 'enabled'; }, 2000); } if the disabled attribute isn't specified, the button inherits its disabled state from its parent element.
... <input type="button" value="button 1"> <input type="button" value="button 2"> <input type="button" value="button 3"> </fieldset> const button = document.queryselector('input'); const fieldset = document.queryselector('fieldset'); button.addeventlistener('click', disablebutton); function disablebutton() { fieldset.disabled = true; window.settimeout(function() { fieldset.disabled = false; }, 2000); } note: firefox will, unlike other browsers, by default, persist the dynamic disabled state of a <button> across page loads.
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Browser detection using the user agent - HTTP
problems like these can be avoided by testing for support of the feature itself instead: var islookbehindsupported = false; try { new regexp("(?<=)"); islookbehindsupported = true; } catch (err) { // if the agent doesn't support lookbehinds, the attempted // creation of a regexp object using that syntax throws and // islookbehindsupported remains false.
... var hastouchscreen = false; if ("maxtouchpoints" in navigator) { hastouchscreen = navigator.maxtouchpoints > 0; } else if ("msmaxtouchpoints" in navigator) { hastouchscreen = navigator.msmaxtouchpoints > 0; } else { var mq = window.matchmedia && matchmedia("(pointer:coarse)"); if (mq && mq.media === "(pointer:coarse)") { hastouchscreen = !!mq.matches; } else if ('orientation' in window) { ...
...function(mq) { for (var i=0,len=mql.length|0; i<len; i=i+1|0) if (mql[i][0] === mq) mql.splice(i, 1); mq.removelistener(whenmediachanges); } : listentomediaquery; var orientationchanged = false; addeventlistener("orientationchange", function(){ orientationchanged = true; }, passive_listener_option); addeventlistener("resize", settimeout.bind(0,function(){ if (orientationchanged && !mediaqueryupdated) for (var i=0,len=mql.length|0; i<len; i=i+1|0) mql[i][1]( mql[i][0] ); mediaqueryupdated = orientationchanged = false; },0)); which part of the user agent ...
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Proxy Auto-Configuration (PAC) file - HTTP
in chrome (versions 52 to 73), you can disable this by setting pachttpsurlstrippingenabled to false in policy or by launching with the --unsafe-pac-url command-line flag (in chrome 74, only the flag works, and from 75 onward, there is no way to disable path-stripping; as of chrome 81, path-stripping does not apply to http urls, but there is interest in changing this behavior to match https); in firefox, the preference is network.proxy.autoconfig_url.include_path.
... examples isplainhostname("www.mozilla.org") // false isplainhostname("www") // true dnsdomainis() syntax dnsdomainis(host, domain) parameters host is the hostname from the url.
... examples dnsdomainis("www.mozilla.org", ".mozilla.org") // true dnsdomainis("www", ".mozilla.org") // false localhostordomainis() syntax localhostordomainis(host, hostdom) parameters host the hostname from the url.
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A re-introduction to JavaScript (JS tutorial) - JavaScript
e it as an operand to any mathematical operation, the result will also be nan: nan + 5; // nan you can test for nan using the built-in isnan() function: isnan(nan); // true javascript also has the special values infinity and -infinity: 1 / 0; // infinity -1 / 0; // -infinity you can test for infinity, -infinity and nan values using the built-in isfinite() function: isfinite(1 / 0); // false isfinite(-infinity); // false isfinite(nan); // false the parseint() and parsefloat() functions parse a string until they reach a character that isn't valid for the specified number format, then return the number parsed up to that point.
... javascript has a boolean type, with possible values true and false (both of which are keywords.) any value can be converted to a boolean according to the following rules: false, 0, empty strings (""), nan, null, and undefined all become false.
... you can perform this conversion explicitly using the boolean() function: boolean(''); // false boolean(234); // true however, this is rarely necessary, as javascript will silently perform this conversion when it expects a boolean, such as in an if statement (see below).
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Enumerability and ownership of properties - JavaScript
enumerable properties are those properties whose internal enumerable flag is set to true, which is the default for properties created via simple assignment or via a property initializer (properties defined via object.defineproperty and such default enumerable to false).
... detection can occur by simplepropertyretriever.thegetmethodyouwant(obj).indexof(prop) > -1 iteration can occur by simplepropertyretriever.thegetmethodyouwant(obj).foreach(function (value, prop) {}); (or use filter(), map(), etc.) var simplepropertyretriever = { getownenumerables: function(obj) { return this._getpropertynames(obj, true, false, this._enumerable); // or could use for..in filtered with hasownproperty or just this: return object.keys(obj); }, getownnonenumerables: function(obj) { return this._getpropertynames(obj, true, false, this._notenumerable); }, getownenumerablesandnonenumerables: function(obj) { return this._getpropertynames(obj, true, false, this._enumerableandnotenumerable...
...); // or just use: return object.getownpropertynames(obj); }, getprototypeenumerables: function(obj) { return this._getpropertynames(obj, false, true, this._enumerable); }, getprototypenonenumerables: function(obj) { return this._getpropertynames(obj, false, true, this._notenumerable); }, getprototypeenumerablesandnonenumerables: function(obj) { return this._getpropertynames(obj, false, true, this._enumerableandnotenumerable); }, getownandprototypeenumerables: function(obj) { return this._getpropertynames(obj, true, true, this._enumerable); // or could use unfiltered for..in }, getownandprototypenonenumerables: function(obj) { return this._getpropertynames(obj, true, true, this._notenumerable); }...
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Grammar and types - JavaScript
var input; if (input === undefined) { dothis(); } else { dothat(); } the undefined value behaves as false when used in a boolean context.
... var a; a + 2; // evaluates to nan when you evaluate a null variable, the null value behaves as 0 in numeric contexts and as false in boolean contexts.
...true and false.
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Intl.Collator() constructor - JavaScript
possible values are "true" and "false".
...possible values are "upper", "lower", or "false" (use the locale's default).
...possible values are true and false; the default is false.
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Map - JavaScript
other operations on the data fail: wrongmap.has('bla') // false wrongmap.delete('bla') // false console.log(wrongmap) // map { bla: 'blaa', bla2: 'blaaa2' } the correct usage for storing data in the map is through the set(key, value) method.
... let contacts = new map() contacts.set('jessie', {phone: "213-555-1234", address: "123 n 1st ave"}) contacts.has('jessie') // true contacts.get('hilary') // undefined contacts.set('hilary', {phone: "617-555-4321", address: "321 s 2nd st"}) contacts.get('jessie') // {phone: "213-555-1234", address: "123 n 1st ave"} contacts.delete('raymond') // false contacts.delete('jessie') // true console.log(contacts.size) // 1 constructor map() creates a new map object.
... map.prototype.delete(key) returns true if an element in the map object existed and has been removed, or false if the element does not exist.
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Object.isExtensible() - JavaScript
object.preventextensions(empty); object.isextensible(empty); // === false // sealed objects are by definition non-extensible.
... var sealed = object.seal({}); object.isextensible(sealed); // === false // frozen objects are also by definition non-extensible.
... var frozen = object.freeze({}); object.isextensible(frozen); // === false non-object coercion in es5, if the argument to this method is not an object (a primitive), then it will cause a typeerror.
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Proxy - JavaScript
obj[prop] : 37; } }; const p = new proxy({}, handler); p.a = 1; p.b = undefined; console.log(p.a, p.b); // 1, undefined console.log('c' in p, p.c); // false, 37 no-op forwarding proxy in this example, we are using a native javascript object to which our proxy will forward all operations that are applied to it.
... let view = new proxy({ selected: null }, { set: function(obj, prop, newval) { let oldval = obj[prop]; if (prop === 'selected') { if (oldval) { oldval.setattribute('aria-selected', 'false'); } if (newval) { newval.setattribute('aria-selected', 'true'); } } // the default behavior to store the value obj[prop] = newval; // indicate success return true; } }); let i1 = view.selected = document.getelementbyid('item-1'); //giving error here, i1 is null console.log(i1.getattribute('aria-selected')); // 'true' let i2 = view.selected = ...
...document.getelementbyid('item-2'); console.log(i1.getattribute('aria-selected')); // 'false' console.log(i2.getattribute('aria-selected')); // 'true' note: even if selected: !null, then giving oldval.setattribute is not a function value correction and an extra property the products proxy object evaluates the passed value and converts it to an array if needed.
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TypedArray.prototype.every() - JavaScript
return value true if the callback function returns a truthy value for every array element; otherwise, false.
... description the every method executes the provided callback function once for each element present in the typed array until it finds one where callback returns a falsy value (a value that becomes false when converted to a boolean).
... if such an element is found, the every method immediately returns false.
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Less than (<) - JavaScript
the less than operator (<) returns true if the left operand is less than the right operand, and false otherwise.
... otherwise javascript attempts to convert non-numeric types to numeric values: boolean values true and false are converted to 1 and 0 respectively.
... if either value is nan, the operator returns false.
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Logical AND (&&) - JavaScript
if a value can be converted to false, the value is so-called falsy.
... examples of expressions that can be converted to false are: null; nan; 0; empty string ("" or '' or ``); undefined.
...see example: function a(){ console.log('called a'); return false; } function b(){ console.log('called b'); return true; } console.log( a() && b() ); // logs "called a" due to the function call, // then logs false (which is the resulting value of the operator) operator precedence the following expressions might seem equivalent, but they are not, because the && operator is executed before the || operator (see operator precedence).
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Logical OR (||) - JavaScript
if a value can be converted to false, the value is so-called falsy.
... examples of expressions that can be converted to false are: null; nan; 0; empty string ("" or '' or ``); undefined.
...see example: function a(){ console.log('called a'); return false; } function b(){ console.log('called b'); return true; } console.log( b() || a() ); // logs "called b" due to the function call, // then logs true (which is the resulting value of the operator) operator precedence the following expressions might seem equivalent, but they are not, because the && operator is executed before the || operator (see operator precedence).
...And 2 more matches

Strict equality (===) - JavaScript
if the operands are of different types, return false.
... if either operand is nan, return false.
... booleans must be both true or both false.
...And 2 more matches

in operator - JavaScript
// arrays let trees = ['redwood', 'bay', 'cedar', 'oak', 'maple'] 0 in trees // returns true 3 in trees // returns true 6 in trees // returns false 'bay' in trees // returns false (you must specify the index number, not the value at that index) 'length' in trees // returns true (length is an array property) symbol.iterator in trees // returns true (arrays are iterable, works only in es2015+) // predefined objects 'pi' in math // returns true // custom objects let mycar = {make: 'honda', model: 'accord', year: 1998} 'make' in my...
... let color1 = new string('green') 'length' in color1 // returns true let color2 = 'coral' // generates an error (color2 is not a string object) 'length' in color2 using in with deleted or undefined properties if you delete a property with the delete operator, the in operator returns false for that property.
... let mycar = {make: 'honda', model: 'accord', year: 1998} delete mycar.make 'make' in mycar // returns false let trees = new array('redwood', 'bay', 'cedar', 'oak', 'maple') delete trees[3] 3 in trees // returns false if you set a property to undefined but do not delete it, the in operator returns true for that property.
...And 2 more matches

instanceof - JavaScript
// defining constructors function c() {} function d() {} let o = new c() // true, because: object.getprototypeof(o) === c.prototype o instanceof c // false, because d.prototype is nowhere in o's prototype chain o instanceof d o instanceof object // true, because: c.prototype instanceof object // true c.prototype = {} let o2 = new c() o2 instanceof c // true // false, because c.prototype is nowhere in // o's prototype chain anymore o instanceof c d.prototype = new c() // add c to [[prototype]] linkage of d let o3 = new d() o3 instanc...
...for instance, [] instanceof window.frames[0].array will return false, because array.prototype !== window.frames[0].array and arrays inherit from the former.
... let simplestr = 'this is a simple string' let mystring = new string() let newstr = new string('string created with constructor') let mydate = new date() let myobj = {} let mynonobj = object.create(null) simplestr instanceof string // returns false, string literal is not an object mystring instanceof string // returns true newstr instanceof string // returns true mystring instanceof object // returns true myobj instanceof object // returns true, every object literal has object.prototype as prototype ({}) instanceof object // returns true, same case as above mynonobj instanceof object // returns false, prototype is end ...
...And 2 more matches

Classes and Inheritance - Archive of obsolete content
consider the following: let circle = circle(2, 3, 5); circle instanceof shape; // => false since instances of circle inherit from shape, we definitely want the result of this expression to be true.
...otherwise, it repeats the comparison for the prototype of the right hand side, and so on, until either it returns true, or the prototype becomes null, in which case it returns false.
...consequently, overriding a method is as simple as providing a new definition on the prototype of the subclass: circle.prototype.draw = function (ctx) { ctx.beginpath(); ctx.arc(this.x, this.y, this.radius, 0, 2 * math.pi, false); ctx.fill(); }; with this definition in place, we get: let shape = shape(2, 3); shape.draw(); // error: not yet implemented let circle = circle(2, 3, 5); circle.draw(); // typeerror: ctx is not defined which is the behavior we were aiming for.
... property, let's redefine the constructor for the class circle in terms of class: var circle = class({ extends: shape, initialize: function(x, y, radius) { shape.prototype.initialize.call(this, x, y); this.radius = radius; }, draw: function (context) { context.beginpath(); context.arc(this.x, this.y, this.radius, 0, 2 * math.pi, false); context.fill(); } }); unlike the definition of circle in the previous section, we no longer have to override its prototype, or set its constructor property.

tabs/utils - Archive of obsolete content
if false, make the new tab the selected tab.
... optional, defaults to false.
...optional, defaults to false.
... returns boolean : true if the tab is open, otherwise false.

ui/frame - Archive of obsolete content
ation, you need to specify "*" as the origin: window.parent.postmessage("ping", "*"); if the frame script has received a message from the add-on already, it can use the origin property of the event object passed to the message hander: // listen for messages from the add-on, and send a reply window.addeventlistener("message", function(event) { event.source.postmessage("pong", event.origin) }, false); this frame script listens to change events on the "city-selector" <select> element, and sends a message to the add-on containing the value for the newly selected element.
.../city-info.html", onmessage: (e) => { updateweather(e.data); } }); var toolbar = toolbar({ name: "city-info", title: "city info", items: [frame] }); function updateweather(location) { frame.postmessage(weather[location], frame.url); } to listen to these messages in the frame script, add a listener to the window's message event: window.addeventlistener("message", updateweather, false); function updateweather(message) { var label = window.document.getelementbyid("weather"); label.textcontent = message.data; } from add-on to a specific frame you can send a message from the main add-on code to the frame hosted by a particular browser window.
... to receive such messages in the frame script, listen for the window's message event: window.addeventlistener("message", handlepong, false); sending json in all cases, you can send a string as a message or a json object.
...ar } = require("sdk/ui/toolbar"); var frame = new frame({ url: "./frame.html" }); var toolbar = toolbar({ name: "my-toolbar", title: "my toolbar", items: [frame] }); frame.postmessage("ping", frame.url); frame scripts can receive these messages using window.addeventlistener(): function ponged(message) { label.textcontent = message.data; } window.addeventlistener("message", ponged, false); to send a message only to the frame instance hosted by a specific browser window call postmessage() on the source property of the object passed into any of the frame's event listeners.

Forms related code snippets - Archive of obsolete content
+ " " + this.current.getfullyear(); this.container.appendchild(this.otbody); }; function ondocclick (opssevt) { const oevt = opssevt || /* ie */ window.event; var boutside = true; for (var onode = oevt.target || /* ie */ oevt.srcelement; onode; onode = onode.parentnode) { if (onode.classname === sprefs + "-calendar" || onode.classname === sdpclass) { boutside = false; break; } } if (boutside) { return; } ainstances[onode.id.replace(rbgnnan, "")].container.style.zindex = nzindex++; } function onheadclick () { const bismonth = rmonth.test(this.id), ndelta = rdecrease.test(this.id) ?
..."getmonth" : "getfullyear"]() + ndelta); othiscal.writedays(); return false; } function ondayclick () { const othiscal = ainstances[this.id.replace(rbgnandend, "")]; othiscal.target.value = (this.innerhtml / 100).tofixed(2).substr(-2) + "\/" + (othiscal.current.getmonth() + 1) + "\/" + othiscal.current.getfullyear(); othiscal.container.parentnode.removechild(othiscal.container); return false; } function buildcalendars () { const afields = document.getelementsbyclassname(sdpclass), nlen = afields.length; for (var nitem = 0; nitem < nlen; new datepicker(afields[nitem++])); } const /* customizable by us...
...addeventlistener("load", buildcalendars, false) : window.attachevent ?
...document.addeventlistener("mousedown", ondocclick, false) : document.attachevent ?

On page load - Archive of obsolete content
//messenger/content/messenger.xul navigator from seamonkey chrome://navigator/content/navigator.xul attaching a script attach a script to your overlay (see "attaching a script to an overlay") that adds a load event listener to appcontent element (browsers) or messagepane (mail): window.addeventlistener("load", function load(event){ window.removeeventlistener("load", load, false); //remove listener, no longer needed myextension.init(); },false); var myextension = { init: function() { var appcontent = document.getelementbyid("appcontent"); // browser if(appcontent){ appcontent.addeventlistener("domcontentloaded", myextension.onpageload, true); } var messagepane = document.getelementbyid("messagepane"); // mail if(messagepane){ mess...
...to attach to the unload event in above example you can use the "pagehide" event like this: appcontent.addeventlistener("pagehide", myextension.onpageunload, false); for appcontent and similarly for messagepane messagepane.addeventlistener("pagehide", myextension.onpageunload, false); and add your code to onpageunload method.
... if(gbrowser) gbrowser.addeventlistener("domcontentloaded", this.onpageload, false); }, onpageload: function(aevent) { var doc = aevent.originaltarget; // doc is document that triggered the event var win = doc.defaultview; // win is the window for the doc // test desired conditions and do something // if (doc.nodename != "#document") return; // only documents // if (win != win.top) return; //only top window.
... // if (win.frameelement) return; // skip iframes/frames alert("page is loaded \n" +doc.location.href); } } window.addeventlistener("load", function load(event){ window.removeeventlistener("load", load, false); //remove listener, no longer needed myextension.init(); },false); references if you need to have a more complicated listener (not just onload), use progress listeners.

Install Manifests - Archive of obsolete content
the default value is false.
... skinnable a true or false value property that tells the application whether the (complete) theme can be skinned by lightweight themes/personas: examples <em:skinnable>true</em:skinnable> strictcompatibility a boolean value indicating if the add-on should be enabled when the version of the application is greater than its max version.
... by default, the value of this property is false meaning that the compatibility checking will not be performed against the max version.
... examples <em:translator>janez novak</em:translator> <em:translator>kari nordmann</em:translator> unpack a true or false value that tells the application whether the extension requires its files be unpacked into a directory in order to work or whether the extension can be loaded direct from the xpi.

Listening to events in Firefox extensions - Archive of obsolete content
} b.addeventlistener("event", callback, false) where b is the browser or tabbrowser you wish to watch for events from.
...the pageshow event uses a boolean property called persisted that is set to false on the initial load.
...this property is set to false if the page is not cached by the browser and set to true if the page is cached by the browser.
... when this property is set to false, the unload handler, if present, fires immediately after the pagehide event.

Chapter 3: Introduction to XUL—How to build a more intuitive UI - Archive of obsolete content
note: with attributes like hidden, collapsed, and disabled, which take boolean values, setting disabled="false" in xul can have unintended consequences.
...so when changing the attribute’s value using a dom function for example, do not use setattribute('disabled', false) — instead, use removeattribute('disabled').
... var item = document.getelementbyid('menu-item-custom'); function handlecommandevent(aevent) { alert('ok'); item.removeeventlistener('command', handlecommandevent, false); item.parentnode.removechild(item); } item.addeventlistener('command', handlecommandevent, false); listing 11: additions and deletions using a dynamic event listener special menu items much like input elements in html, menuitem elements can operate like checkboxes and radio buttons by setting their type attributes.
... <checkbox label="checkbox checked" checked="true"/> <checkbox label="checkbox unchecked" checked="false"/> listing 11: checkboxes in different state figure 11: output from listing 11 radio buttons radio buttons in html are multiple input elements grouped by assigning them all the same name attribute.

Chapter 5: Let's build a Firefox extension - Archive of obsolete content
// restore session (event handler) restore: function(event) { }, // delete session (event handler) clear: function(event) { }, // dynamically generate menu items (event handler) createmenu: function(event) { }, // read file _readfile: function(afile) { }, // write file _writefile: function(afile, adata) { }, }; window.addeventlistener("load", function(){ gsessionstore.init(); }, false); window.addeventlistener("unload", function(){ gsessionstore.uninit(); }, false); wrap methods and variables as properties of objects you’ll note that in listing 15, i’ve defined a lot of different methods and variables as properties of a single object, gsessionstore.
... listing 20: content for restore method restore: function(event) { var filename = event.target.getattribute("filename"); var file = this._dir.clone(); file.append(filename); var state = this._readfile(file); var ss = components.classes["@mozilla.org/browser/sessionstore;1"] .getservice(components.interfaces.nsisessionstore); ss.setwindowstate(window, state, false); }, clear method this uses the directoryentries property of the nslfile interface to delete all files within the directory you got earlier.
... listing 21: content for clear method clear: function(event) { event.preventbubble(); var fileenum = this._dir.directoryentries; while (fileenum.hasmoreelements()) { var file = fileenum.getnext().queryinterface(components.interfaces.nsifile); file.remove(false); // debug dump("sessionstore> clear: " + file.leafname + "\n"); } }, _readfile method reads the nslfile object passed as a parameter, and returns its contents as a text string.
...if true, causes a confirmation dialog to appear; if false, deletes immediately.

Adding windows and dialogs - Archive of obsolete content
let somevalue = 2; let returnvalue = { accepted : false , result : "" }; window.opendialog( "chrome://xulschoolhello/content/somedialog.xul", "xulschoolhello-some-dialog", "chrome,centerscreen", somevalue, returnvalue); // you can send as many extra parameters as you need.
...the only constant rule is that clicking on ok and cancel will close the dialog unless your associated function returns false.
... you should avoid returning false, though, specially with the cancel button.
... <checkbox id="xulschoolhello-some-checkbox" label="&xulschoolhello.sometext.label;" checked="false" persist="checked" /> setting the id attribute of the element is mandatory if you want the persist attribute to work.

Observer Notifications - Archive of obsolete content
you should normally set the third parameter to false.
... getservice(components.interfaces.nsiobserverservice); observerservice.addobserver(testobserver, "xulschoolhello-test-topic", false); you should come up with a notification topic that is unique so you know it will not conflict with firefox or other extensions topics.
... getservice(components.interfaces.nsiobserverservice); this._observerservice.addobserver(this, "xulschoolhello-test-topic", false); }, /** * unitializes this object.
... */ observe : function(asubject, atopic, adata) { if (atopic == "xulschoolhello-test-topic") { asubject.queryinterface(ci.nsisupportsstring); window.alert("subject: " + asubject.data); // => "this is a test" window.alert("data: " + adata); // => "hello" } } } window.addeventlistener( "load", function() { xulschoolchrome.browseroverlay.init(); }, false); window.addeventlistener( "unload", function() { xulschoolchrome.browseroverlay.uninit(); }, false); in the observe method the notification topic is verified because you can have one observer listening to several topics.

Introducing the Audio API extension - Archive of obsolete content
controls="true" style="width: 512px;"> </audio> <script> function loadedmetadata() { channels = audio.mozchannels; rate = audio.mozsamplerate; framebufferlength = audio.mozframebufferlength; } var audio = document.getelementbyid('audio-element'); audio.addeventlistener('loadedmetadata', loadedmetadata, false); </script> </body> </html> the mozaudioavailable event as the audio is played, sample data is made available to the audio layer and the audio buffer (size defined in mozframebufferlength) gets filled with those samples.
...event) { var framebuffer = event.framebuffer; var t = event.time; var text = "samples at: " + t + "\n"; text += framebuffer[0] + " " + framebuffer[1]; raw.innerhtml = text; } var raw = document.getelementbyid('raw'); var audio = document.getelementbyid('audio-element'); audio.addeventlistener('mozaudioavailable', audioavailable, false); audio.addeventlistener('loadedmetadata', loadedmetadata, false); </script> </body> </html> creating an audio stream it is also possible to create and setup an <audio> element for raw writing from script (i.e., without a src attribute).
... autolatency = false; } processing an audio stream since the mozaudioavailable event and the mozwriteaudio() method both use float32array values, it is possible to take the output of one audio stream and pass it directly (or process first and then pass) to a second.
... a2.mozsetup(a1.mozchannels, a1.mozsamplerate); } function audioavailable(event) { // write the current framebuffer var framebuffer = event.framebuffer; writeaudio(framebuffer); } a1.addeventlistener('mozaudioavailable', audioavailable, false); a1.addeventlistener('loadedmetadata', loadedmetadata, false); function writeaudio(audio) { buffers.push(audio); // if there's buffered data, write that while(buffers.length > 0) { var buffer = buffers.shift(); var written = a2.mozwriteaudio(buffer); // // if all data wasn't written, keep it in the buffers: if(written < buffer.length) { buffers.unshift(buffer.slice(...

command - Archive of obsolete content
false otherwise.
...false otherwise.
...false otherwise.
...false otherwise.

tooltip - Archive of obsolete content
noautohide type: boolean if this attribute is set to false or omitted, the tooltip will automatically disappear after a few seconds.
...returning false from this event handler prevents the popup from appearing.
... iscontextmenu the iscontextmenu argument should be true for context menus and false for all other types of popups.
...if attributesoverride is false, the attribute is only used if the position argument is empty.

wizard - Archive of obsolete content
if this property is false, the user cannot navigate to the next page.
...set to false to disallow moving to the next page.
...if this property is false, the user cannot navigate to the previous page.
...set to false to disallow moving to the previous page.

Monitoring plugins - Archive of obsolete content
service you must create a class with an observe method which receives 3 parameters (subject, topic and data) as well as a register method that contains the following code: var observerservice = components.classes["@mozilla.org/observer-service;1"] .getservice (components.interfaces.nsiobserverservice); observerservice.addobserver(this, "experimental-notify-plugin-call", false); observing as discussed above, to specify what you want done when a notification arrives your class must have an observe method, receiving 3 parameters (subject, topic and data).
... code: var observerservice = components.classes["@mozilla.org/observer-service;1"] .getservice(components.interfaces.nsiobserverservice); observerservice.removeobserver(this, "experimental-notify-plugin-call"); skeleton observer class below is a skeleton class that you may use to listen to runtime notifications: function pluginobserver() { this.registered = false; this.register(); //takes care of registering this class with observer services as an observer for plugin runtime notifications } pluginwatcherobserver.prototype = { observe: function(subject, topic, data) { if (topic == "experimental-notify-plugin-call") //in case your class is registered to listen to other topics //this gets executed each time a runtime notification arriv...
...es // --your code goes here-- } }, //takes care of registering the observer services for the "experimental-notify-plugin-call" topic register: function() { if (this.registered == false) { //this check prevents double registration -- something you want to avoid!!
... var observerservice = components.classes["@mozilla.org/observer-service;1"] .getservice(components.interfaces.nsiobserverservice); observerservice.addobserver(this, "experimental-notify-plugin-call", false); this.registered = true; } }, //unregisters from the observer services unregister: function() { if (this.registered == true) { var observerservice = components.classes["@mozilla.org/observer-service;1"] .getservice(components.interfaces.nsiobserverservice); observerservice.removeobserver(this, "experimental-notify-plugin-call"); this.registered = false; } } } additional resources more information on the observer service: nsiobserverservi...

NPFullPrint - Archive of obsolete content
false: (default) plug-in renders its area of the page only (for embedded plug-in).
...should always be false.
... false: display print dialogs so user can choose printer, other options.
...if you want an embedded plug-in to simply render its area of the page, set pluginprinted to false and return immediately; the browser calls npp_print again with the npembedprint substructure of npprint.

NPN_SetValue - Archive of obsolete content
variable values the function can set: nppvpluginwindowbool: sets windowed/windowless mode for plugin display; true=windowed, false=windowless nppvplugintransparentbool: sets transparent mode for display of a plugin; true=transparent, false=opaque nppvjavaclass nppvpluginwindowsize nppvplugintimerinterval nppvpluginscriptableinstance nppvpluginscriptableiid nppvjavascriptpushcallerbool: specifies whether you are pushing or popping the jscontext off the stack nppvpluginkeeplibraryinmemory: tells browser that th...
...to set windowless operation, call npn_setvalue with nppvpluginwindowbool as the variable parameter and false as the value parameter.
...to specify an opaque mode, the plugin calls npn_setvalue with nppvplugintransparentbool for the variable parameter and false for the value parameter.
...} so the proper way to call this function from a plug-in would be: bool bwindowed = false; npn_setvalue(npp, nppvpluginwindowbool, ( void *)bwindowed); see also npp_new, npn_getvalue, npp_setvalue, npp_getvalue ...

XForms Select1 Element - Archive of obsolete content
xhtml widget characteristics analogous widgets is <html:select/> visual grouping by choices element is supported selection="open" is supported if incremental attribute value is false, the bound node is updated when the select1 control is blurred (i.e.
... loses focus), otherwise it is updated upon item selection xul widget characteristics analogous widgets are <html:select/> and <xul:menulist/> visual grouping by choices element isn't implemented selection="open" attribute isn't supported if incremental attribute value is false, the bound node is updated when the select control is blurred (i.e.
...characteristics analogous widgets are <html:select size="5"/> and <xul:listbox/> visual grouping by choices element isn't implemented selection="open" attribute isn't supported if incremental attribute value is false, the bound node is updated when the select control is blurred (i.e.
...characteristics appearance attribute contains the value full there are no analogue widgets in xhtml or in xul visual grouping by choices element is supported selection="open" attribute isn't supported if incremental attribute value is false then bound node is updated when item is blurred examples <xf:model> <xf:instance> <data xmlns=""> <values>g</values> </data> </xf:instance> </xf:model> <xf:select1 ref="/data/values"> <xf:choices> <xf:label>green colors</xf:label> <xf:item> <xf:label>pale green</xf:label> <xf:value>pg</xf:value> </xf:item> <xf:item> <xf:label>green</xf:label> <xf:value>g</xf:v...

Audio for Web games - Game development
let's add some javascript to make this work: var myaudio = document.getelementbyid('myaudio'); var buttons = document.getelementsbytagname('button'); var stoptime = 0; for (var i = 0; i < buttons.length; i++) { buttons[i].addeventlistener('click', function() { myaudio.currenttime = this.getattribute("data-start"); stoptime = this.getattribute("data-stop"); myaudio.play(); }, false); } myaudio.addeventlistener('timeupdate', function() { if (this.currenttime > stoptime) { this.pause(); } }, false); note: you can try out our audio sprite player live on jsfiddle.
... to see this in action, let's lay out some separate tracks: <section id="tracks"> <ul> <li data-loading="true"> <a href="leadguitar.mp3" class="track">lead guitar</a> <p class="loading-text">loading...</p> <button data-playing="false" aria-decribedby="guitar-play-label"> <span id="guitar-play-label">play</span> </button> </li> <li data-loading="true"> <a href="bassguitar.mp3" class="track">bass guitar</a> <p class="loading-text">loading...</p> <button data-playing="false" aria-describedby="bass-play-label"> <span id="bass-play-label">play</span> </button> </li> <li...
... data-loading="true"> <a href="drums.mp3" class="track">drums</a> <p class="loading-text">loading...</p> <button data-playing="false" aria-describedby="drums-play-label"> <span id="drums-play-label">play</span> </button> </li> <li data-loading="true"> <a href="horns.mp3" class="track">horns</a> <p class="loading-text">loading...</p> <button data-playing="false" aria-describedby="horns-play-label"> <span id="horns-play-label">play</span> </button> </li> <li data-loading="true"> <a href="clav.mp3" class="track">clavi</a> <p class="loading-text">loading...</p> <button data-playing="false" aria-describedby="clavi-play-label"> <span id="clavi-play-label">play</span> </button> </li> <...
...ur <li> elements, grab the correct file for each one and then allow playback by hiding the "loading" text and displaying the play button: trackels.foreach((el, i) => { // get children const anchor = el.queryselector('a'); const loadtext = el.queryselector('p'); const playbutton = el.queryselector('button'); // load file loadfile(anchor.href).then((track) => { // set loading to false el.dataset.loading = 'false'; // hide loading text loadtext.style.display = 'none'; // show button playbutton.style.display = 'inline-block'; // allow play on click playbutton.addeventlistener('click', function() { // check if context is in suspended state (autoplay policy) if (audioctx.state === 'suspended') { audioctx.resume(); } ...

Implementing controls using the Gamepad API - Game development
the first one is fired when the browser detects the connection of a new gamepad while the second one is fired when a gamepad is disconnected (either physically by the user or due to inactivity.) in the demo, the gamepadapi object is used to store everything related to the api: var gamepadapi = { controller: {}, turbo: false, connect: function() {}, disconnect: function() {}, update: function() {}, buttonpressed: function() {}, buttons: [], buttonscache: [], buttonsstatus: [], axesstatus: [] }; the buttons array contains the xbox 360 button layout: buttons: [ 'dpad-up','dpad-down','dpad-left','dpad-right', 'start','back','axis-left','axis-right', 'lb','rb','power','a','b','x','y', ], this can...
...(we could use the gamepad.connected boolean for this purpose, but we wanted to have a separate variable for turning on turbo mode without needing to have a gamepad connected, for reasons explained above.) disconnect: function(evt) { gamepadapi.turbo = false; delete gamepadapi.controller; console.log('gamepad disconnected.'); }, the disconnect function sets the gamepad.turbo property to false and removes the variable containing the gamepad object.
... buttonpressed: function(button, hold) { var newpress = false; // loop through pressed buttons for(var i=0,s=gamepadapi.buttonsstatus.length; i<s; i++) { // if we found the button we're looking for...
... // set the boolean variable to true newpress = true; // if we want to check the single press if(!hold) { // loop through the cached states from the previous frame for(var j=0,p=gamepadapi.buttonscache.length; j<p; j++) { // if the button was already pressed, ignore new press if(gamepadapi.buttonscache[j] == button) { newpress = false; } } } } } return newpress; }, there are two types of action to consider for a button: a single press and a hold.

Extra lives - Game development
e existing scoretext definition inside your create() function: livestext = game.add.text(game.world.width-5, 5, 'lives: '+lives, { font: '18px arial', fill: '#0095dd' }); livestext.anchor.set(1,0); lifelosttext = game.add.text(game.world.width*0.5, game.world.height*0.5, 'life lost, click to continue', { font: '18px arial', fill: '#0095dd' }); lifelosttext.anchor.set(0.5); lifelosttext.visible = false; the livestext and lifelosttext objects look very similar to the scoretext one — they define a position on the screen, the actual text to display, and the font styling.
... the lifelosttext will be shown only when the life is lost, so its visibility is initially set to false.
...ple instances of the text styling are replaced with the variable: scoretext = game.add.text(5, 5, 'points: 0', textstyle); livestext = game.add.text(game.world.width-5, 5, 'lives: '+lives, textstyle); livestext.anchor.set(1,0); lifelosttext = game.add.text(game.world.width*0.5, game.world.height*0.5, 'life lost, click to continue', textstyle); lifelosttext.anchor.set(0.5); lifelosttext.visible = false; this way changing the font in one variable will apply the changes to every place it is used.
...een() function definition at the end of our code: function ballleavescreen() { lives--; if(lives) { livestext.settext('lives: '+lives); lifelosttext.visible = true; ball.reset(game.world.width*0.5, game.world.height-25); paddle.reset(game.world.width*0.5, game.world.height-5); game.input.ondown.addonce(function(){ lifelosttext.visible = false; ball.body.velocity.set(150, -150); }, this); } else { alert('you lost, game over!'); location.reload(); } } instead of instantly printing out the alert when you lose a life, we first subtract one life from the current number and check if it's a non-zero value.

XInclude - MDN Web Docs Glossary: Definitions of Web-related terms
d is allowed if (href === '' || href === null) { // points to same document if empty (null is equivalent to empty string) href = null; // set for uniformity in testing below if (parse === 'xml' && xpointer === null) { alert('there must be an xpointer attribute present if "href" is empty an parse is "xml"'); return false; } } else if (href.match(/#$/, '') || href.match(/^#/, '')) { alert('fragment identifiers are disallowed in an xinclude "href" attribute'); return false; } var j; var xincludeparent = xinclude.parentnode; try { netscape.security.privilegemanager.enableprivilege('...
...universalxpconnect universalbrowserread'); // necessary with file:///-located files trying to reach external sites if (href !== null) { var response, responsetype; var request = new xmlhttprequest(); request.open('get', href, false); request.setrequestheader('if-modified-since', 'thu, 1 jan 1970 00:00:00 gmt'); request.setrequestheader('cache-control', 'no-cache'); if (accept) { request.setrequestheader('accept', accept); } if (acceptlanguage) { request.setrequestheader('accept-language', acceptlanguage); } switch (parse) { ...
... responsetype = 'responsetext'; break; case null: case 'xml': responsetype = 'responsexml'; break; default: alert('xinclude element contains an invalid "parse" attribute value'); return false; break; } request.send(null); if((request.status === 200 || request.status === 0) && request[responsetype] !== null) { response = request[responsetype]; if (responsetype === 'responsexml') { // apply xpointer (only xpath1() subset is ...
... } // need to make a whole new request apparently since cannot convert the encoding after receiving it (to know what the encoding was) var request2 = new xmlhttprequest(); request2.overridemimetype('text/plain; charset='+encodingtype); request2.open('get', href, false); request2.setrequestheader('if-modified-since', 'thu, 1 jan 1970 00:00:00 gmt'); request2.setrequestheader('cache-control', 'no-cache'); request2.send(null); response = request2[responsetype]; // update the response for processing } ...

A first splash into JavaScript - Learn web development
cument.body.append(resetbutton); resetbutton.addeventlistener('click', resetgame); } function resetgame() { guesscount = 1; const resetparas = document.queryselectorall('.resultparas p'); for(let i = 0 ; i < resetparas.length ; i++) { resetparas[i].textcontent = ''; } resetbutton.parentnode.removechild(resetbutton); guessfield.disabled = false; guesssubmit.disabled = false; guessfield.value = ''; guessfield.focus(); lastresult.style.backgroundcolor = 'white'; randomnumber = math.floor(math.random() * 100) + 1; } </script> </body> </html> have a go at playing it — familiarize yourself with the game before you move on.
...for example, if you want to simply add a new text string to an existing one and return the result, you could do this: name += ' says hello!'; this is equivalent to name = name + ' says hello!'; when we are running true/false tests (for example inside conditionals — see below) we use comparison operators.
... for example: operator name example === strict equality (is it exactly the same?) 5 === 2 + 4 // false 'chris' === 'bob' // false 5 === 2 + 3 // true 2 === '2' // false; number versus string !== non-equality (is it not the same?) 5 !== 2 + 4 // true 'chris' !== 'bob' // true 5 !== 2 + 3 // false 2 !== '2' // true; number versus string < less than 6 < 10 // true 20 < 10 // false > greater than 6 > 10 // false 20 > 10 // true conditionals returning to our checkguess() function, i think it's safe to say that we don't want it to just spit out a placeholder message.
...add the following code, again to the bottom of your javascript: function resetgame() { guesscount = 1; const resetparas = document.queryselectorall('.resultparas p'); for (let i = 0 ; i < resetparas.length ; i++) { resetparas[i].textcontent = ''; } resetbutton.parentnode.removechild(resetbutton); guessfield.disabled = false; guesssubmit.disabled = false; guessfield.value = ''; guessfield.focus(); lastresult.style.backgroundcolor = 'white'; randomnumber = math.floor(math.random() * 100) + 1; } this rather long block of code completely resets everything to how it was at the start of the game, so the player can have another go.

Componentizing our Svelte app - Learn web development
add the following variable definitions at the bottom of the <script> section of the todo component: let editing = false // track editing mode let name = todo.name // hold the name of the todo being edited we have to decide what events our todo component will emit: we could emit different events for the status toggle and editing of the name.
... add the following set of functions below your previous function to handle these actions: function oncancel() { name = todo.name // restores name to its initial value and editing = false // and exit editing mode } function onsave() { update({ name: name }) // updates todo name editing = false // and exit editing mode } function onremove() { dispatch('remove', todo) // emit remove event } function onedit() { editing = true // enter editing mode } function ontoggle() { updat...
... when editing is true, for example, svelte will show the update form; when it's false, it will remove it from the dom and add in the checkbox.
... the <input>'s value property will be bound to the name variable, and the buttons to cancel and save the changes call oncancel() and onsave() respectively (we added those functions earlier): when oncancel() is invoked, name is restored to its original value (when passed in as a prop) and we exit editing mode (by setting editing to false).

Cookies Preferences in Mozilla
network.cookie.alwaysacceptsessioncookies default value: false only used if network.cookie.lifetimepolicy is set to 1 true = accepts session cookies without prompting false = prompts for session cookies network.cookie.thirdparty.sessiononly default value: false true = restrict third party cookies to the session only false = no restrictions on third party cookies network.cookie.maxnumber default value: 1000 configures the maximum amount of cookies t...
...e is from 0-65535, rfc 2109 and 2965 require this to be at least 300 network.cookie.maxperhost default value: 50 configures the maximum amount of cookies to be stored per host valid range is from 0-65535, rfc 2109 and 2965 require this to be at least 20 network.cookie.disablecookieformailnews default value: true true = do not accept any cookies from within mailnews or from mail-style uris false = allow cookies in these situations this preference is applicable to all versions of seamonkey.
... network.cookie.prefsmigrated default value: false migration pref for users with older profiles (before mozilla 1.7).
...(the old prefs are network.cookie.lifetime.enabled, network.cookie.lifetime.behavior, and network.cookie.warnaboutcookies.) true = prefs have been migrated false = migrate prefs on next startup original document information author(s): mike connor last updated date: may 22, 2004 copyright information: portions of this content are © 1998–2007 by individual mozilla.org contributors; content available under a creative commons license | details.

Index
true means to verify that the module is in fips mode, while false means to verify that the module is not in fips mode.
... -fips [true | false] enable (true) or disable (false) fips 140-2 compliance for the default nss module.
... to verify that status of fips mode, run the -chkfips command with either a true or false flag (it doesn't matter which).
... modutil -chkfips false -dbdir sql:/home/my/sharednssdb/ fips mode enabled.

NSS 3.15.4 release notes
bug 919877 - (cve-2013-1740) when false start is enabled, libssl will sometimes return unencrypted, unauthenticated data from pr_recv new in nss 3.15.4 new functionality implemented ocsp querying using the http get method, which is the new default, and will fall back to the http post method.
... new functions cert_forcepostmethodforocsp cert_getsubjectnamedigest cert_getsubjectpublickeydigest ssl_peercertificatechain ssl_recommendedcanfalsestart ssl_setcanfalsestartcallback new types cert_rev_m_force_post_method_for_ocsp: when this flag is used, libpkix will never attempt to use the http get method for ocsp requests; it will always use post.
... improved ssl/tls false start.
... in addition to enabling the ssl_enable_false_start option, an application must now register a callback using the ssl_setcanfalsestartcallback function.

NSS tools : modutil
true means to verify that the module is in fips mode, while false means to verify that the module is not in fips mode.
... -fips [true | false] enable (true) or disable (false) fips 140-2 compliance for the default nss module.
... to verify that status of fips mode, run the -chkfips command with either a true or false flag (it doesn't matter which).
... modutil -chkfips false -dbdir sql:/home/my/sharednssdb/ fips mode enabled.

ssltyp.html
freeitem when pr_false, free only the structure pointed to.
...when freeitem is not pr_false, also frees the item structure itself.
... freeitem when pr_false, free only the structure pointed to.
...when freeitem is not pr_false, also zeroes and frees the item structure itself.

NSS tools : modutil
true means to verify that the module is in fips mode, while false means to verify that the module is not in fips mode.
... -fips [true | false] enable (true) or disable (false) fips 140-2 compliance for the default nss module.
... to verify that status of fips mode, run the -chkfips command with either a true or false flag (it doesn't matter which).
... modutil -chkfips false -dbdir sql:/home/my/sharednssdb/ fips mode enabled.

JSBool
js_true has been replaced by just true and in the same way js_false by false.
...js_true indicates success; js_false indicates an error or exception occurred.
...js_true is (jsbool) 1 and js_false is (jsbool) 0.
...instead, use jsval_true and jsval_false, and use boolean_to_jsval and jsval_to_boolean to convert.

JS_AddArgumentFormatter
otherwise it returns js_false.
... fromjs jsbool js_true if the conversion function should convert from jsval values to c values; js_false if the conversion function should convert from c values to jsval values.
... callback description the conversion function should return true on success, and return false after reporting an error or detecting an already-reported error.
...when called from js_pushargumentsva, the formatter is invoked thus: formatter(cx, "aa...", js_false, &sp, &ap); where js_false for fromjs means to wrap the c values at ap according to the format specifier and store them at sp, updating ap and sp appropriately.

JS_PreventExtensions
before then, js_preventextensions did not accept a succeeded argument; in those cases where *succeeded would be set to false, js_preventextensions would throw a typeerror and return false.
... for example, if making the object requires an allocation, and that allocation fails, out-of-memory might be reported, and js_preventextensions would return false.
... var target = {}; var handler = {}; var pair = proxy.revocable(target, handler); var proxy = pair.proxy; var revoke = pair.revoke; revoke(); // bool succeeded; // bool rv = js_preventextensions(cx, proxy, &succeeded); // // rv == false, succeeded is indeterminate the second case occurs when no internal error is encountered, but the object simply refuses to be made non-extensible.
... var target = {}; var handler = { preventextensions: function(obj) { return false; } }; var obj = new proxy(target, handler); // bool succeeded; // bool rv = js_preventextensions(cx, obj, &succeeded); // // rv == true, succeeded == false note that as with most jsapi methods, *succeeded is only set if js_preventextensions returns true (that is, does not fail).

Places utilities for JavaScript
the all take in the same argument and return a boolean true or false, so i'm just going to list them all in one lump: boolean nodeisfolder(anode) determines whether or not a resultnode is a bookmark folder or not.
... return type return true if the node is a folder, false otherwise.
...for managing,you want this to be false, for menus and such, you want this to be true.
... checkurlsecurity(aurinode) parameters aurinode a uri node return type return true if it's safe to open the node in the browser, false otherwise.

IAccessibleAction
s_false if there is nothing to return, [out] value is null.
...s_false if there are no relations, [out] values are null and 0 respectively.
...s_false if there is nothing to return, [out] value is null.
...s_false if there is nothing to return, [out] value is null.

IAccessibleApplication
return value s_false if there is nothing to return, [out] value is null.
... return value s_false if there is nothing to return, [out] value is null.
... return value s_false if there is nothing to return, [out] value is null.
... return value s_false if there is nothing to return, [out] value is null.

IAccessibleHyperlink
s_false if there is nothing to return, [out] value is null.
...s_false if there is nothing to return, [out] value is null.
...[propget] hresult valid( [out] boolean valid ); parameters valid true if the referenced target is still valid and false otherwise.
... return value s_false if there is nothing to return, [out] value is false.

nsIAccessibleTable
return value true if the cell is selected, false if the cell is not selected.
... return value true if the column is selected, false if the column is not selected.
... return value true if the table is probably for layout, false if the table is probably not for layout.
... return value true if the row is selected, false if the row is not selected.

nsIAnnotationService
return value returns true, if an annotation exists for given uri, otherwise returns false.
... return value returns true, if an annotation exists for given item, otherwise returns false.
... aoverwritedest if you want to overwrite existing annotation, set this parameter to true, or else set it to false.
... aoverwritedest if you want to overwrite existing annotation, set this parameter to true or else false.

nsIAppShellService
this will usually be false on all non-mac platforms.
... ashowwindow obsolete since gecko 1.8 the window remains invisible if pr_false.
... caninteract if false and ui is needed, will fail.
... amodal true if awindow is becoming modal or false if awindow is becoming nonmodal (or being closed).

nsICategoryManager
you must pass false for this parameter.
... exceptions thrown ns_error_invalid_arg this error is returned if areplace is false and the category entry already has a value, or if apersist is true.
...you should always pass false for this parameter.
...let categorymanager = cc['@mozilla.org/categorymanager;1']; categorymanager.getservice(ci.nsicategorymanager).deletecategoryentry('gecko-content-viewers', content_type, false); // update pref manager to prevent plugins from loading in future var stringtypes = ''; var types = []; var pref_disabled_plugin_types = 'plugin.disable_full_page_plugin_for_types'; if (services.prefs.prefhasuservalue(pref_disabled_plugin_types)) { stringtypes = services.prefs.getcharpref(pref_disabled_plugin_types); } if (stringtypes !== '') { types = stringtypes.split(','); } if (ty...

nsIClipboardDragDropHooks
otherwise, false to indicates to the operating system that drop is not allowed.
...otherwise, false to show the drag is canceled (does not go to operating system).
...otherwise, false to indicate that the copy/drag is canceled, does not go to operating system.
...otherwise, false to indicate the action was not overridden, do built-in behavior.

nsICryptoHash
if false, then the returned value is binary data.
...inputstream); // open for reading istream.init(f, 0x01, 0444, 0); var ch = components.classes["@mozilla.org/security/hash;1"] .createinstance(components.interfaces.nsicryptohash); // we want to use the sha256 algorithm ch.init(ch.sha256); // this tells updatefromstream to read the entire file const pr_uint32_max = 0xffffffff; ch.updatefromstream(istream, pr_uint32_max); // pass false here to get binary data back var hash = ch.finish(false); // return the two-digit hexadecimal code for a byte function tohexstring(charcode) { return ("0" + charcode.tostring(16)).slice(-2); } // convert the binary hash data to a hex string.
...the single parameter to this method is false in this example to return binary data.
...charset = "utf-8"; // result is an out parameter, // result.value will contain the array length var result = {}; // data is an array of bytes var data = converter.converttobytearray(str, result); var ch = components.classes["@mozilla.org/security/hash;1"] .createinstance(components.interfaces.nsicryptohash); ch.init(ch.sha256); ch.update(data, data.length); var hash = ch.finish(false); // return the two-digit hexadecimal code for a byte function tohexstring(charcode) { return ("0" + charcode.tostring(16)).slice(-2); } // convert the binary hash data to a hex string.

nsIDOMMouseScrollEvent
ctrlkeyarg true if the control key was down when the event occurred, otherwise false.
... altkeyarg true if the alt key was down when the event occurred, otherwise false.
... shiftkeyarg true if the shift key was down when the event occurred, otherwise false.
... metakeyarg true if the meta key was down when the event occurred, otherwise false.

nsIEditorSpellCheck
if there are no available dictionaries, the return value is false.
...boolean checkcurrentword( in wstring suggestedword ); parameters suggestedword missing description return value true if the specified word is misspelled; otherwise false.
... return value true if the word is misspelled; otherwise false.
...if false, only the first occurrence is replaced.

nsIHttpChannelInternal
this may throw an ns_error_not_available exception if accessed when the channel's endpoints haven't been determined yet, or any time the nsihttpactivityobserver.isactive attribute is false.
...this may throw an ns_error_not_available exception if accessed when the channel's endpoints haven't been determined yet, or any time the nsihttpactivityobserver.isactive attribute is false.
...this may throw an ns_error_not_available exception if accessed when the channel's endpoints haven't been determined yet, or any time the nsihttpactivityobserver.isactive attribute is false.
...this may throw an ns_error_not_available exception if accessed when the channel's endpoints haven't been determined yet, or any time the nsihttpactivityobserver.isactive attribute is false.

nsIMsgDBView
if false kb are used.
...false if it is disabled.
...false otherwise.
...if false then replace current selection.

Component; nsIPrefBranch
false holds a strong reference to aobserver.
...in particular, this method will return false for such a preference and the preference will not be saved to a file by nsiprefservice.savepreffile().
...false the preference only has a default value.
...false the preference is not locked.

nsIProcess
isrunning boolean true if the process is running, otherwise false.
... void run( in boolean blocking, [array, size_is(count)] in string args, in unsigned long count ); parameters blocking if true, this method will block until the process terminates; if false, the method returns immediately.
... void runw( in boolean blocking, [array, size_is(count)] in wstring args, in unsigned long count ); parameters blocking if true, this method will block until the process terminates; if false, the method returns immediately.
...var args = ["argument1", "argument2"]; process.run(false, args, args.length); see also nsifile nsiprocess2 obsolete since gecko 1.9.2 ...

nsIProcessScriptLoader
it's possible that the child process for this chromemessagesender is not yet available at the time of the loadprocessscript() call, and if you pass false in this situation, your process script won't be loaded.
...for example data:,dump("foo\n"); aallowdelayedload boolean if this flag is false, the process script will only be loaded into child processes that are already running at the time of the call.
...the return value is a list of pairs [<url>, false].
...each script is returned as a pair: [<url>, false].

nsITextInputProcessorCallback
example of simple js-ime: var simpleime = { _hasfocus: false, _hasrightstocompose: false, _tip: null, _callback: function simpleime_callback(atip, anotification) { try { switch (anotification.type) { case "request-to-commit": atip.commitcomposition(); break; case "request-to-cancel": atip.cancelcomposition(); break; case "notify-focus": this._hasfocus = true; ...
... break; case "notify-blur": this._hasfocus = false; break; case "notify-detached": this._hasfocus = false; this._hasrightstocompose = false; break; } return true; } catch (e) { return false; } }, setcomposition: function simpleime_setcomposition(atext, aclauses, acaret) { if (!this._tip) { this._tip = components.classes["@mozilla.org/text-input-processor;1"].
... createinstance(components.interfaces.nsitextinputprocessor); } if (!this._tip.begininputtransaction(window, this._callback)) { return false; } ...
...otherwise, false.

nsIWindowMediator
, ci: interfaces} = components; var windowlistener = { onopenwindow: function (awindow) { // wait for the window to finish loading let domwindow = awindow.queryinterface(ci.nsiinterfacerequestor).getinterface(ci.nsidomwindowinternal || ci.nsidomwindow); domwindow.addeventlistener("load", function () { domwindow.removeeventlistener("load", arguments.callee, false); //this removes this load function from the window //window has now loaded now do stuff to it //as example this will add a function to listen to tab select and will fire alert in that window if (domwindow.gbrowser && domwindow.gbrowser.tabcontainer) { domwindow.gbrowser.tabcontainer.addeventlistener('tabselect', function () { ...
... domwindow.alert('tab was selected') }, false); } }, false); }, onclosewindow: function (awindow) {}, onwindowtitlechange: function (awindow, atitle) {} }; //to register services.wm.addlistener(windowlistener); //services.wm.removelistener(windowlistener); //once you want to remove this listener execute removelistener, currently its commented out so you can copy paste this code in scratchpad and see it work native code only!calculatezposition a window wants to be moved in z-order.
...back to front if false.
...back to front if false.

Version, UI, and Status Information - Plugins
if false is returned, windowless plug-ins will not work, and the developer must provide alternatives.
...*/ return false; } else /* plug-in is running in a navigator version */ /* that has windowless support */ return true; } detecting windowless support on other platforms browser implementations on other platforms did not have windowless plug-in support at the time it was added to ms windows and mac os x, so a different method must be used to detect whether the browser provides support.
... bool has_windowless() { npbool supportswindowless = false; nperror ret = npn_getvalue(instance, npnvsupportswindowless, &supportswindowless); return ret == nperr_no_error && supportswindowless; } reloading a plug-in when the browser starts up, it loads all the plug-ins it finds in the plugins directory for the platform.
... void npn_reloadplugins(npbool reloadpages); the reloadpages parameter is a boolean that indicates whether to reload the page (true) or not (false).

Debugger.Frame - Firefox Developer Tools
this allows the code using each debugger instance to place whatever properties it likes on its debugger.frame instances, without worrying about interfering with other debuggers.) when the debuggee pops a stack frame (say, because a function call has returned or an exception has been thrown from it), the debugger.frame instance referring to that frame becomes inactive: its live property becomes false, and accessing its other properties or calling its methods throws an exception.
... live true if the frame this debugger.frame instance refers to is still on the stack; false if it has completed execution or been popped in some other way.
... generator true if this frame is a generator frame, false otherwise.
... constructing true if this frame is for a function called as a constructor, false otherwise.

Debugger.Script - Firefox Developer Tools
false otherwise.
...false otherwise.
...the object has the following properties: linenumber: the line number for which offset is an entry point columnnumber: the column number for which offset is an entry point isentrypoint: true if the offset is a column entry point, as would be reported by getallcolumnoffsets(); otherwise false.
... isincatchscope([offset]) if the instance refers to a jsscript, this is true if this offset falls within the scope of a try block, and false otherwise.

Intensive JavaScript - Firefox Developer Tools
th its immediate caller: const iterations = 50; const multiplier = 1000000000; function calculateprimes(iterations, multiplier) { var primes = []; for (var i = 0; i < iterations; i++) { var candidate = i * (multiplier * math.random()); var isprime = true; for (var c = 2; c <= math.sqrt(candidate); ++c) { if (candidate % c === 0) { // not prime isprime = false; break; } } if (isprime) { primes.push(candidate); } } return primes; } function dopointlesscomputationswithblocking() { var primes = calculateprimes(iterations, multiplier); pointlesscomputationsbutton.disabled = false; console.log(primes); } we're just running a (very inefficient) primality test 50 times, for some quite large numbers.
... it's pretty simple to split up calculateprimes(): we will just calculate primality for each number in a separate function: function dopointlesscomputationswithrequestanimationframe() { function testcandidate(index) { // finishing condition if (index == iterations) { console.log(primes); pointlesscomputationsbutton.disabled = false; return; } // test this number var candidate = index * (multiplier * math.random()); var isprime = true; for (var c = 2; c <= math.sqrt(candidate); ++c) { if (candidate % c === 0) { // not prime isprime = false; break; } } if (isprime) { primes.push(candidate); } // schedule the next var testfunction = ...
... the main thread code would look something like this: const iterations = 50; const multiplier = 1000000000; var worker = new worker("js/calculate.js"); function dopointlesscomputationsinworker() { function handleworkercompletion(message) { if (message.data.command == "done") { pointlesscomputationsbutton.disabled = false; console.log(message.data.primes); worker.removeeventlistener("message", handleworkercompletion); } } worker.addeventlistener("message", handleworkercompletion, false); worker.postmessage({ "multiplier": multiplier, "iterations": iterations }); } the main difference here, compared with the original, is that we need to: create a worker send it a message when ...
...lier); self.postmessage({ "command":"done", "primes": primes }); } function calculateprimes(iterations, multiplier) { var primes = []; for (var i = 0; i < iterations; i++) { var candidate = i * (multiplier * math.random()); var isprime = true; for (var c = 2; c <= math.sqrt(candidate); ++c) { if (candidate % c === 0) { // not prime isprime = false; break; } } if (isprime) { primes.push(candidate); } } return primes; } in the worker, we have to listen for a message telling us to start, and send a "done" message back when we are done.

Cache.match() - Web APIs
it defaults to false.
... ignoremethod: a boolean that, when set to true, prevents matching operations from validating the request http method (normally only get and head are allowed.) it defaults to false.
...it defaults to false.
...if our if() condition is false, then this fetch handler won't intercept the request.

Event() - Web APIs
the default is false.
...the default is false.
...the default is false.
... example // create a look event that bubbles up and cannot be canceled const evt = new event("look", {"bubbles":true, "cancelable":false}); document.dispatchevent(evt); // event can be dispatched from any element, not only the document mydiv.dispatchevent(evt); specifications specification status comment domthe definition of 'event()' in that specification.

HTMLSelectElement - Web APIs
this attribute is the empty string if the control is not a candidate for constraint validation (willvalidate is false), or it satisfies its constraints.
...it is false if any conditions bar it from constraint validation.
...if the element fails its constraints, the browser fires a cancelable invalid event at the element (and returns false).
...if there are problems, it fires a cancelable invalid event at the element, and returns false; if there are no problems, it returns true.

IDBKeyRange - Web APIs
keys ≥ x idbkeyrange.lowerbound(x) all keys > x idbkeyrange.lowerbound(x, true) all keys ≤ y idbkeyrange.upperbound(y) all keys < y idbkeyrange.upperbound(y, true) all keys ≥ x && ≤ y idbkeyrange.bound(x, y) all keys > x &&< y idbkeyrange.bound(x, y, true, true) all keys > x && ≤ y idbkeyrange.bound(x, y, true, false) all keys ≥ x &&< y idbkeyrange.bound(x, y, false, true) the key = z idbkeyrange.only(z) a key is in a key range if the following conditions are true: the lower value of the key range is one of the following: undefined less than key value equal to key value if loweropen is false.
... the upper value of the key range is one of the following: undefined greater than key value equal to key value if upperopen is false.
... idbkeyrange.loweropen read only returns false if the lower-bound value is included in the key range.
... idbkeyrange.upperopen read only returns false if the upper-bound value is included in the key range.

MediaStreamConstraints.audio - Web APIs
syntax var audioconstraints = true | false | mediatrackconstraints; value the value of the audio property can be specified as either of two types: boolean if a boolean value is specified, it simply indicates whether or not an audio track should be included in the returned stream; if it's true, an audio track is included; if no audio source is available or if permission is not given to use the audio source, the call to getusermedia() will fail.
... if false, no audio track is included.
...ment = document.getelementbyid("audio"); let logelement = document.getelementbyid("log"); function log(msg) { logelement.innerhtml += msg + "<br>"; } document.getelementbyid("startbutton").addeventlistener("click", function() { navigator.mediadevices.getusermedia({ audio: true }).then(stream => audioelement.srcobject = stream) .catch(err => log(err.name + ": " + err.message)); }, false); here we see an event handler for a click event which uses getusermedia() to obtain an audio-only stream with no specific constraints, then attaches the resulting stream to an <audio> element once the stream is returned.
...nt = document.getelementbyid("log"); function log(msg) { logelement.innerhtml += msg + "<br>"; } document.getelementbyid("startbutton").addeventlistener("click", function() { navigator.mediadevices.getusermedia({ audio: { samplesize: 8, echocancellation: true } }).then(stream => audioelement.srcobject = stream) .catch(err => log(err.name + ": " + err.message)); }, false); here we see an event handler for a click event which calls getusermedia(), specifying a set of audio constraints requesting that echo cancellation be enabled and that, if possible, the sample rate be 8 bits per sample instead of the more common 16 bits (possibly as a bandwidth saving measure).

MediaStreamConstraints.video - Web APIs
syntax var videoconstraints = true | false | mediatrackconstraints; value the value of the video property can be specified as either of two types: boolean if a boolean value is specified, it simply indicates whether or not a video track should be included in the returned stream; if it's true, a video track is included; if no video source is available or if permission is not given to use the video source, the call to getusermedia() will fail.
... if false, no video track is included.
...nt = document.getelementbyid("video"); let logelement = document.getelementbyid("log"); function log(msg) { logelement.innerhtml += msg + "<br>"; } document.getelementbyid("startbutton").addeventlistener("click", function() { navigator.mediadevices.getusermedia({ video: true }).then(stream => videoelement.srcobject = stream) .catch(err => log(err.name + ": " + err.message)); }, false); here we see an event handler for a click event which uses getusermedia() to obtain a video-only stream with no specific constraints, then attaches the resulting stream to a <video> element once the stream is returned.
...elementbyid("log"); function log(msg) { logelement.innerhtml += msg + "<br>"; } document.getelementbyid("startbutton").addeventlistener("click", function() { navigator.mediadevices.getusermedia({ video: { width: 160, height: 120, framerate: 15 } }).then(stream => videoelement.srcobject = stream) .catch(err => log(err.name + ": " + err.message)); }, false); here we see an event handler for a click event which calls getusermedia(), specifying a set of video constraints that indicate a preference for a video track whose dimensions are as close as possible to 160x120 pixels, and whose frame rate is as close to 15 frames per second as possible.

MediaStreamTrack.enabled - Web APIs
the enabled property on the mediastreamtrack interface is a boolean value which is true if the track is allowed to render the source stream or false if it is not.
... syntax const enabledflag = track.enabled track.enabled = [true | false] value when true, enabled indicates that the track is permitted to render its actual media to the output.
... when enabled is set to false, the track only generates empty frames.
... usage notes if the mediastreamtrack represents the video input from a camera, disabling the track by setting enabled to false also updates device activity indicators to show that the camera is not currently recording or streaming.

MediaTrackSettings - Web APIs
properties of audio tracks autogaincontrol a boolean which indicates the current value of the autogaincontrol property, which is true if automatic gain control is enabled and is false otherwise.
... echocancellation a boolean indicating the current value of the echocancellation property, specifying true if echo cancellation is enabled, otherwise false.
... noisesuppression a boolean which indicates the current value of the noisesupression property, which is true if noise suppression is enabled and is false otherwise.
...this is false if the video being captured is coming from a foreground (user-visible) source.

Capabilities, constraints, and settings - Web APIs
let videodefaultconstraintstring = '{\n "width": 320,\n "height": 240,\n "framerate": 30\n}'; let audiodefaultconstraintstring = '{\n "samplesize": 16,\n "channelcount": 2,\n "echocancellation": false\n}'; these defaults ask for a pretty common camera configuration, but don't insist on any property being of special importance.
... we also need to set up an event listener to watch for the "start video" button to be clicked: document.getelementbyid("startbutton").addeventlistener("click", function() { startvideo(); }, false); applying constraint set updates next, we set up an event listener for the "apply constraints" button.
...otrack.applyconstraints(videoconstraints).then(function() { videosettingstext.value = json.stringify(videotrack.getsettings(), null, 2); }).catch(handleerror); } if (audiotrack) { audiotrack.applyconstraints(audioconstraints).then(function() { audiosettingstext.value = json.stringify(audiotrack.getsettings(), null, 2); }).catch(handleerror); } } }, false); handling the stop button then we set up the handler for the stop button.
...key == "tab") { let elem = event.target; let str = elem.value; let position = elem.selectionstart; let newstr = str.substring(0, position) + " " + str.substring(position, str.length); elem.value = newstr; elem.selectionstart = elem.selectionend = position + 2; event.preventdefault(); } } videoconstrainteditor.addeventlistener("keydown", keydownhandler, false); audioconstrainteditor.addeventlistener("keydown", keydownhandler, false); show constrainable properties the browser supports the last significant piece of the puzzle: code that displays, for the user's reference, a list of the constrainable properties which their browser supports.

MouseEvent() - Web APIs
"ctrlkey", optional and defaulting to false, of type boolean, that indicates if the ctrl key was simultaneously pressed.
... "shiftkey", optional and defaulting to false, of type boolean, that indicates if the shift key was simultaneously pressed.
... "altkey", optional and defaulting to false, of type boolean, that indicates if the alt key was simultaneously pressed.
... "metakey", optional and defaulting to false, of type boolean, that indicates if the meta key was simultaneously pressed.

MutationObserverInit.subtree - Web APIs
the default value, false, indicates only the target node itself is to be monitored for changes.
... syntax var options = { subtree: true | false } value a boolean value.
... the default, false, indicates that only the target node specified when calling mutationobserver.observe() is to be monitored for changes.
... for example, to watch the target node only for attribute changes, the mutationobserverinit passed into mutationobserver() can be: var options = { attributes: true, subtree: false }; since the default value of subtree is false, line 3 is optional.

Node - Web APIs
node.isdefaultnamespace() accepts a namespace uri as an argument and returns a boolean with a value of true if the namespace is the default namespace on the given node or false if not.
...*/ removeallchildren(document.body) recurse through child nodes the following function recursively calls a callback function for each node contained by a root node (including the root itself): function eachnode(rootnode, callback) { if (!callback) { const nodes = [] eachnode(rootnode, function(node) { nodes.push(node) }) return nodes } if (false === callback(rootnode)) { return false } if (rootnode.haschildnodes()) { const nodes = rootnode.childnodes for (let i = 0, l = nodes.length; i < l; ++i) { if (false === eachnode(nodes[i], callback)) { return } } } } syntax eachnode(rootnode, callback) description recursively calls a function for each descendant node of rootnode (including the root itse...
... if callback is provided, and it returns boolean false when called, the current recursion level is aborted, and the function resumes execution at the last parent's level.
... we use a wrapper function named grep to do the searching: function grep(parentnode, pattern) { const matches = [] let endscan = false eachnode(parentnode, function(node){ if (endscan) { return false } // ignore anything which isn't a text node if (node.nodetype !== node.text_node) { return } if (typeof pattern === "string") { if (-1 !== node.textcontent.indexof(pattern)) { matches.push(node) } } else if (pattern.test(node.textcontent)) { if (!pattern.global) { e...

Page Visibility API - Web APIs
// warn if the browser doesn't support addeventlistener or the page visibility api if (typeof document.addeventlistener === "undefined" || hidden === undefined) { console.log("this demo requires a browser, such as google chrome or firefox, that supports the page visibility api."); } else { // handle page visibility change document.addeventlistener(visibilitychange, handlevisibilitychange, false); // when the video pauses, set the title.
... // this shows the paused videoelement.addeventlistener("pause", function(){ document.title = 'paused'; }, false); // when the video plays, set the title.
... videoelement.addeventlistener("play", function(){ document.title = 'playing'; }, false); } properties added to the document interface the page visibility api adds the following properties to the document interface: document.hidden read only returns true if the page is in a state considered to be hidden to the user, and false otherwise.
... //startsimulation and pausesimulation defined elsewhere function handlevisibilitychange() { if (document.hidden) { pausesimulation(); } else { startsimulation(); } } document.addeventlistener("visibilitychange", handlevisibilitychange, false); specifications specification status comment page visibility (second edition) recommendation initial definition.

PaymentRequest.PaymentRequest() - Web APIs
the default is false.
...the default is false.
...the default is false.
...the default is false.

Pointer Lock API - Web APIs
if ("onpointerlockchange" in document) { document.addeventlistener('pointerlockchange', lockchangealert, false); } else if ("onmozpointerlockchange" in document) { document.addeventlistener('mozpointerlockchange', lockchangealert, false); } function lockchangealert() { if(document.pointerlockelement === canvas || document.mozpointerlockelement === canvas) { console.log('the pointer lock status is now locked'); // do something useful in response } else { console.log('the pointer lock s...
... document.addeventlistener('pointerlockerror', lockerror, false); document.addeventlistener('mozpointerlockerror', lockerror, false); function lockerror(e) { alert("pointer lock failed"); } note: until firefox 50 the above events were prefixed with moz in firefox.
... // pointer lock event listener // hook pointer lock state change events for different browsers document.addeventlistener('pointerlockchange', lockchangealert, false); document.addeventlistener('mozpointerlockchange', lockchangealert, false); this function checks the pointlockelement property to see if it is our canvas.
... function lockchangealert() { if (document.pointerlockelement === canvas || document.mozpointerlockelement === canvas) { console.log('the pointer lock status is now locked'); document.addeventlistener("mousemove", updateposition, false); } else { console.log('the pointer lock status is now unlocked'); document.removeeventlistener("mousemove", updateposition, false); } } the updateposition() function updates the position of the ball on the canvas (x and y), and also includes if() statements to check whether the ball has gone off the edges of the canvas.

RTCDataChannel.negotiated - Web APIs
the read-only rtcdatachannel property negotiated indicates whether the rtcdatachannel's connection was negotiated by the web app (true) or by the webrtc layer (false).
... the default is false.
... syntax var negotiated = adatachannel.negotiated; value true if the rtcdatachannel's connection was negotiated by the web app itself; false if the negotiation was handled by the webrtc layer.
... the default is false.

ServiceWorkerRegistration.showNotification() - Web APIs
the default is false.
...if this value is absent or false, the desktop version of chrome will auto-minimize notifications after approximately twenty seconds.
... the default value is false.
...the default value is false.

SourceBuffer - Web APIs
sourcebuffer.updating changes from true to false.
...sourcebuffer.updating changes from true to false.
...sourcebuffer.updating changes from true to false.
... sourcebuffer.onupdatestart fired whenever the value of sourcebuffer.updating transitions from false to true.

SubtleCrypto.wrapKey() - Web APIs
*/ function getkeymaterial() { const password = window.prompt("enter your password"); const enc = new textencoder(); return window.crypto.subtle.importkey( "raw", enc.encode(password), {name: "pbkdf2"}, false, ["derivebits", "derivekey"] ); } /* given some key material and some random salt derive an aes-kw key using pbkdf2.
...*/ function getkeymaterial() { const password = window.prompt("enter your password"); const enc = new textencoder(); return window.crypto.subtle.importkey( "raw", enc.encode(password), {name: "pbkdf2"}, false, ["derivebits", "derivekey"] ); } /* given some key material and some random salt derive an aes-gcm key using pbkdf2.
...*/ function getkeymaterial() { const password = window.prompt("enter your password"); const enc = new textencoder(); return window.crypto.subtle.importkey( "raw", enc.encode(password), {name: "pbkdf2"}, false, ["derivebits", "derivekey"] ); } /* given some key material and some random salt derive an aes-cbc key using pbkdf2.
...*/ function getkeymaterial() { const password = window.prompt("enter your password"); const enc = new textencoder(); return window.crypto.subtle.importkey( "raw", enc.encode(password), {name: "pbkdf2"}, false, ["derivebits", "derivekey"] ); } /* given some key material and some random salt derive an aes-gcm key using pbkdf2.

TouchEvent() - Web APIs
"ctrlkey", optional and defaulting to false, of type boolean, that indicates if the ctrl key was simultaneously pressed.
... "shiftkey", optional and defaulting to false, of type boolean, that indicates if the shift key was simultaneously pressed.
... "altkey", optional and defaulting to false, of type boolean, that indicates if the alt key was simultaneously pressed.
... "metakey", optional and defaulting to false, of type boolean, that indicates if the meta key was simultaneously pressed.

Multi-touch interaction - Web APIs
// log events flag var logevents = false; // touch point cache var tpcache = new array(); register event handlers event handlers are registered for all four touch event types.
... // ev.preventdefault(); if (logevents) log("touchmove", ev, false); // to avoid too much color flashing many touchmove events are started, // don't update the background if two touch points are active if (!(ev.touches.length == 2 && ev.targettouches.length == 2)) update_background(ev); // set the target element's border to dashed to give a clear visual // indication the element received a move event.
... function end_handler(ev) { ev.preventdefault(); if (logevents) log(ev.type, ev, false); if (ev.targettouches.length == 0) { // restore background and border to original values ev.target.style.background = "white"; ev.target.style.border = "1px solid black"; } } application ui the application uses <div> elements for the touch areas and provides buttons to enable logging and clear the log.
...false : true; } function log(name, ev, printtargetids) { var o = document.getelementsbytagname('output')[0]; var s = name + ": touches = " + ev.touches.length + " ; targettouches = " + ev.targettouches.length + " ; changedtouches = " + ev.changedtouches.length; o.innerhtml += s + " "; if (printtargetids) { s = ""; for (var i=0; i < ev.targettouches.leng...

Simple color animation - Web APIs
text-align : center; } canvas { display : block; width : 280px; height : 210px; margin : auto; padding : 0; border : none; background-color : black; } button { display : inline-block; font-size : inherit; margin : auto; padding : 0.6em; } window.addeventlistener("load", function setupanimation (evt) { "use strict" window.removeeventlistener(evt.type, setupanimation, false); // a variable to hold a timer that drives the animation.
... var button = document.queryselector("#animation-onoff"); var verb = document.queryselector("strong"); function startanimation(evt) { button.removeeventlistener(evt.type, startanimation, false); button.addeventlistener("click", stopanimation, false); verb.innerhtml="stop"; // setup animation loop by redrawing every second.
... drawanimation(); } function stopanimation(evt) { button.removeeventlistener(evt.type, stopanimation, false); button.addeventlistener("click", startanimation, false); verb.innerhtml="start"; // stop animation by clearing the timer.
... function getrandomcolor() { return [math.random(), math.random(), math.random()]; } }, false); the source code of this example is also available on github.

A simple RTCDataChannel sample - Web APIs
connectbutton = document.getelementbyid('connectbutton'); disconnectbutton = document.getelementbyid('disconnectbutton'); sendbutton = document.getelementbyid('sendbutton'); messageinputbox = document.getelementbyid('message'); receivebox = document.getelementbyid('receivebox'); // set event listeners for user interface widgets connectbutton.addeventlistener('click', connectpeers, false); disconnectbutton.addeventlistener('click', disconnectpeers, false); sendbutton.addeventlistener('click', sendmessage, false); } this is quite straightforward.
...these handlers can do whatever's needed, but in this example, all we need to do is update the user interface: function handlelocaladdcandidatesuccess() { connectbutton.disabled = true; } function handleremoteaddcandidatesuccess() { disconnectbutton.disabled = false; } the only thing we do here is disable the "connect" button when the local peer is connected and enable the "disconnect" button when the remote peer connects.
... when the local peer experiences an open or close event, the handlesendchannelstatuschange() method is called: function handlesendchannelstatuschange(event) { if (sendchannel) { var state = sendchannel.readystate; if (state === "open") { messageinputbox.disabled = false; messageinputbox.focus(); sendbutton.disabled = false; disconnectbutton.disabled = false; connectbutton.disabled = true; } else { messageinputbox.disabled = true; sendbutton.disabled = true; connectbutton.disabled = false; disconnectbutton.disabled = true; } } } if the channel's state has changed to "open", that in...
... sendchannel.close(); receivechannel.close(); // close the rtcpeerconnections localconnection.close(); remoteconnection.close(); sendchannel = null; receivechannel = null; localconnection = null; remoteconnection = null; // update user interface elements connectbutton.disabled = false; disconnectbutton.disabled = true; sendbutton.disabled = true; messageinputbox.value = ""; messageinputbox.disabled = true; } this starts by closing each peer's rtcdatachannel, then, similarly, each rtcpeerconnection.

Taking still photos with WebRTC - Web APIs
(function() { var width = 320; // we will scale the photo width to this var height = 0; // this will be computed based on the input stream var streaming = false; var video = null; var canvas = null; var photo = null; var startbutton = null; those variables are: width whatever size the incoming video is, we're going to scale the resulting image to be 320 pixels wide.
... function startup() { video = document.getelementbyid('video'); canvas = document.getelementbyid('canvas'); photo = document.getelementbyid('photo'); startbutton = document.getelementbyid('startbutton'); get the media stream the next task is to get the media stream: navigator.mediadevices.getusermedia({ video: true, audio: false }) .then(function(stream) { video.srcobject = stream; video.play(); }) .catch(function(err) { console.log("an error occurred: " + err); }); here, we're calling mediadevices.getusermedia() and requesting a video stream (without audio).
... video.addeventlistener('canplay', function(ev){ if (!streaming) { height = video.videoheight / (video.videowidth/width); video.setattribute('width', width); video.setattribute('height', height); canvas.setattribute('width', width); canvas.setattribute('height', height); streaming = true; } }, false); this callback does nothing unless it's the first time it's been called; this is tested by looking at the value of our streaming variable, which is false the first time this method is run.
... handle clicks on the button to capture a still photo each time the user clicks the startbutton, we need to add an event listener to the button, to be called when the click event is issued: startbutton.addeventlistener('click', function(ev){ takepicture(); ev.preventdefault(); }, false); this method is simple enough: it just calls our takepicture() function, defined below in the section capturing a frame from the stream, then calls event.preventdefault() on the received event to prevent the click from being handled more than once.

Using DTMF with WebRTC - Web APIs
let dialstring = "12024561111"; let callerpc = null; let receiverpc = null; let dtmfsender = null; let hasaddtrack = false; let mediaconstraints = { audio: true, video: false }; let offeroptions = { offertoreceiveaudio: 1, offertoreceivevideo: 0 }; let dialbutton = null; let logelement = null; these are, in order: dialstring the dtmf string the caller will send when the "dial" button is clicked.
...we want an audio-only connection, so video is false, while audio is true.
... window.addeventlistener("load", function() { logelement = document.queryselector(".log"); dialbutton = document.queryselector("#dial"); dialbutton.addeventlistener("click", connectanddial, false); }); starting the connection process when the dial button is clicked, connectanddial() is called.
...if it does, we set hasaddtrack to true; otherwise, we set it to false.

Using IIR filters - Web APIs
the play button html looks like this: <button class="button-play" role="switch" data-playing="false" aria-pressed="false">play</button> and the click event listener starts like so: playbutton.addeventlistener('click', function() { if (this.dataset.playing === 'false') { srcnode = playsourcenode(audioctx, sample); ...
... }, false); the toggle that turns the iir filter on and off is set up in the similar way.
... first, the html: <button class="button-filter" role="switch" data-filteron="false" aria-pressed="false" aria-describedby="label" disabled></button> the filter button's click handler then connects the iirfilter up to the graph, between the source and the detination: filterbutton.addeventlistener('click', function() { if (this.dataset.filteron === 'false') { srcnode.disconnect(audioctx.destination); srcnode.connect(iirfilter).connect(audioctx.destination); ...
... }, false); frequency response we only have one method available on iirfilternode instances, getfrequencyresponse(), this allows us to see what is happening to the frequencies of the audio being passed into the filter.

Synchronous and asynchronous requests - Web APIs
var request = new xmlhttprequest(); request.open('get', '/bar/foo.txt', false); // `false` makes the request synchronous request.send(null); if (request.status === 200) { console.log(request.responsetext); } line 3 sends the request.
... mytask.js (the worker): self.onmessage = function (event) { if (event.data === "hello") { var xhr = new xmlhttprequest(); xhr.open("get", "myfile.txt", false); // synchronous request xhr.send(null); self.postmessage(xhr.responsetext); } }; note: the effect is asynchronous, because of the use of the worker.
... window.addeventlistener('unload', logdata, false); function logdata() { var client = new xmlhttprequest(); client.open("post", "/log", false); // third parameter indicates sync xhr.
... window.addeventlistener('unload', logdata, false); function logdata() { navigator.sendbeacon("/log", analyticsdata); } ...

XRWebGLLayerInit.ignoreDepthValues - Web APIs
the default value, false, means the depth buffer will be used, if available.
...if false, the depth buffer's contents are used, if one is present.
...the default is false (depth values are used by default).
... xrsession.updaterenderstate({ baselayer: new xrwebgllayer(xrsession, gl, { alpha: false, ignoredepthvalues: true }); }); specifications specification status comment webxr device apithe definition of 'xrwebgllayerinit.ignoredepthvalues' in that specification.

Using the aria-invalid attribute - Accessibility
values vocabulary: false (default) no errors detected grammar a grammatical error has been detected.
...note that since the default value for aria-required is false, it is not strictly necessary to add the attribute to input.
... <input name="name" id="name" aria-required="true" aria-invalid="false" onblur="checkvalidity('name', ' ', 'invalid name entered (requires both first and last name)');"/> <br /> <input name="email" id="email" aria-required="true" aria-invalid="false" onblur="checkvalidity('email', '@', 'invalid e-mail address');"/> note that it is not necessary to validate the fields immediately on blur; the application could wait until the form is submitted (though this is not necessarily recommended).
...ce of a particular character (in the real world, validation will likely be more sophisticated): function checkvalidity(aid, asearchterm, amsg){ var elem = document.getelementbyid(aid); var invalid = (elem.value.indexof(asearchterm) < 0); if (invalid) { elem.setattribute("aria-invalid", "true"); updatealert(amsg); } else { elem.setattribute("aria-invalid", "false"); updatealert(); } } the snippet below shows the alert functions, which add (or remove) the error message: function updatealert(msg) { var oldalert = document.getelementbyid("alert"); if (oldalert) { document.body.removechild(oldalert); } if (msg) { var newalert = document.createelement("div"); newalert.setattribute("role", "alert"); ...

ARIA Test Cases - Accessibility
at should indicate that it is a toggle button (not a regular button) markup used: role="button" aria-pressed="false" (or true) notes: results: at firefox ie opera safari jaws 9 - - n/a n/a jaws 10 pass in non-v-pc-mode, button's state is announced when pressed, or when toggling it to pressed.
... - - - voiceover (leopard) n/a n/a - fail window-eyes - - - - nvda - n/a - - zoom (leopard) pass n/a pass pass zoomtext - - - - orca - - - - checkbox simple checkbox testcases: set aria-checked="false" for unchecked both remove or set attribute for unchecked case -- also includes an invalid and required checkbox hierarchical (newly added test not in test results yet) dojo nightly build expected at behavior: screen reader should speak the accessible name followed by both the type being checkbox and the state (checked, unchecked).
... markup used: role="checkbox" aria-checked="true" or "false" notes: need testcase where aria-checked attribute is removed instead of set to false results: at firefox ie opera safari jaws 9 - - n/a n/a jaws 10 pass fail (changes not spoken) fail fail voiceover (leopard) n/a n/a - fail window-eyes pass pass fail (unchecked presented as checked, ie exposing incorrect state for no aria-checked attribute) fail fail nvda fail on #2 -- repetitive text spoken, first checkbox toggle speaks incorrect state n/a fail fail zoom (leopard) pass n/a pass pass ...
... markup used: role="checkbox" aria-checked="true" | "false" | "mixed" notes: results: at firefox ie opera safari jaws 9 - - n/a n/a jaws 10 partial pass.

ARIA: feed role - Accessibility
<section role="feed" aria-busy="false"> ...
...if the addition of articles occupies the main browser thread, make sure to set aria-busy="true" on the feed itself, and make sure to set it back to false when processing ends, or the user may not see the updates.
...make sure it's reset to false when the operation is complete or the changes may not become visible.
...for example, setting aria-busy to true during the update operation if needed, and then to false upon completion.

Using media queries - CSS: Cascading Style Sheets
queries involving unknown media types are always false.
... note: a style sheet with a media query attached to its <link> tag will still download even if the query returns false.
... not the not operator is used to negate a media query, returning true if the query would otherwise return false.
...} if a feature doesn't apply to the device on which the browser is running, expressions involving that media feature are always false.

WAI ARIA Live Regions/API Support - Developer guides
aria-relevant on ancestor element container-busy "true" | "false" | "error" "false" the current changes are not yet complete.
... aria-busy on ancestor element container-atomic "true" | "false" "false" is this change inside a region that should always be presented at once.
... aria-atomic on ancestor element event-from-input "true" | "false" (described more below) browser could not calculate this was the root cause of this event explicit user input?
...in iaccessible2, this is retrieved from the object attribute "event-from-input", which will be set to "true" or "false".

Audio and Video Delivery - Developer guides
audiofile.mp3" type="audio/mpeg"> <source src="audiofile.ogg" type="audio/ogg"> <!-- fallback for non supporting browsers goes here --> <a href="audiofile.mp3">download audio</a> <object width="320" height="30" type="application/x-shockwave-flash" data="flashmediaelement.swf"> <param name="movie" value="flashmediaelement.swf" /> <param name="flashvars" value="controls=true&isvideo=false&file=audiofile.mp3" /> </object> </audio> the process is very similar with video — just remember to set isvideo=true in the flashvars value parameters.
... to grab the stream from your webcam, first set up a <video> element: <video id="webcam" width="480" height="360"></video> next, if supported connect the webcam source to the video element: if (navigator.mediadevices) { navigator.mediadevices.getusermedia({ video: true, audio: false }) .then(function onsuccess(stream) { var video = document.getelementbyid('webcam'); video.autoplay = true; video.srcobject = stream; }) .catch(function onerror() { alert('there has been a problem retreiving the streams - are you running on file:/// or did you disallow access?'); }); } else { alert('getusermedia is not supported in this browser.'); } to find out more, ...
...ementbyid('my-control'); function switchstate() { if (myaudio.paused == true) { myaudio.play(); mycontrol.innerhtml = "pause"; } else { myaudio.pause(); mycontrol.innerhtml = "play"; } } function checkkey(e) { if (e.keycode == 32 ) { //spacebar switchstate(); } } mycontrol.addeventlistener('click', function() { switchstate(); }, false); window.addeventlistener( "keypress", checkkey, false ); } you can try this example out here.
... app search in firefox os"> </a> <p>click image to play a video demo of dynamic app search</p> </video> var v = document.queryselector('video'), sources = v.queryselectorall('source'), lastsource = sources[sources.length-1]; lastsource.addeventlistener('error', function(ev) { var d = document.createelement('div'); d.innerhtml = v.innerhtml; v.parentnode.replacechild(d, v); }, false); audio/video javascript libraries a number of audio and video javascript libaries exist.

HTML attribute reference - HTML: Hypertext Markup Language
if a boolean attribute is present, its value is true, and if it’s absent, its value is false.
...</div> to be clear, the values "true" and "false" are not allowed on boolean attributes.
... to represent a false value, the attribute has to be omitted altogether.
... this restriction clears up some common misunderstandings: with checked="false" for example, the element’s checked attribute would be interpreted as true because the attribute is present.

<input type="checkbox"> - HTML: Hypertext Markup Language
additional attributes in addition to the common attributes shared by all <input> elements, "checkbox" inputs support the following attributes: attribute description checked boolean; if present, the checkbox is toggled on by default indeterminate a boolean which, if present, indicates that the value of the checkbox is indeterminate rather than true or false value the string to use as the value of the checkbox when submitting the form, if the checkbox is currently toggled on checked a boolean attribute indicating whether or not this checkbox is checked by default (when the page loads).
... indeterminate if the indeterminate attribute is present on the <input> element defining a checkbox, the checkbox's value is neither true nor false, but is instead indeterminate, meaning that it's state cannot be determined or stated in pure binary terms.
...'click', function(e) { e.preventdefault(); }); for(var i = 0; i < ingredients.length; i++) { ingredients[i].addeventlistener('click', updatedisplay); } function updatedisplay() { var checkedcount = 0; for(var i = 0; i < ingredients.length; i++) { if(ingredients[i].checked) { checkedcount++; } } if(checkedcount === 0) { overall.checked = false; overall.indeterminate = false; } else if(checkedcount === ingredients.length) { overall.checked = true; overall.indeterminate = false; } else { overall.checked = false; overall.indeterminate = true; } } note: if you submit a form with an indeterminate checkbox, the same thing happens as if the checkbox were unchecked — no data is submitted to rep...
...however, most of the validitystates will always be false.

BigInt - JavaScript
const expected = 4n / 2n // ↪ 2n const rounded = 5n / 2n // ↪ 2n, not 2.5n comparisons a bigint is not strictly equal to a number, but it is loosely so: 0n === 0 // ↪ false 0n == 0 // ↪ true a number and a bigint may be compared as usual: 1n < 2 // ↪ true 2n > 1 // ↪ true 2 > 2 // ↪ false 2n > 2 // ↪ false 2n >= 2 // ↪ true they may be mixed in arrays and sorted: const mixed = [4n, 6, -12n, 10, 4, 0, 0n] // ↪ [4n, 6, -12n, 10, 4, 0, 0n] mixed.sort() // default sorting behavior // ↪ [ -12n, 0, 0n, 10, 4n, 4, 6 ] mixed.sort((a, b) => a - b...
...1 : 0)) // ↪ [ -12n, 0, 0n, 4n, 4, 6, 10 ] note that comparisons with object-wrapped bigints act as with other objects, only indicating equality when the same object instance is compared: 0n === object(0n) // false object(0n) === object(0n) // false const o = object(0n) o === o // true conditionals a bigint behaves like a number in cases where: it is converted to a boolean: via the boolean function; when used with logical operators ||, &&, and !; or within a conditional test like an if statement.
... if (0n) { console.log('hello from the if!') } else { console.log('hello from the else!') } // ↪ "hello from the else!" 0n || 12n // ↪ 12n 0n && 12n // ↪ 0n boolean(0n) // ↪ false boolean(12n) // ↪ true !12n // ↪ false !0n // ↪ true constructor bigint() creates a new bigint value.
...ver, you can implement your own tojson method if needed: bigint.prototype.tojson = function() { return this.tostring() } instead of throwing, json.stringify now produces a string like this: json.stringify(bigint(1)) // '"1"' examples calculating primes // returns true if passed bigint is a prime number function isprime(p) { for (let i = 2n; i * i <= p; i++) { if (p % i === 0n) return false; } return true } // takes a bigint as an argument, returns nth prime number as bigint function nthprime(nth) { let maybeprime = 2n let prime = 0n while (nth >= 0n) { if (isprime(maybeprime)) { nth-- prime = maybeprime } maybeprime++ } return prime } nthprime(20n) // ↪ 73n specifications specification ecmascript (ecma-262)the defi...

Generator.prototype.next() - JavaScript
has the value false if the iterator was able to produce the next value in the sequence.
... examples using next() the following example shows a simple generator and the object that the next method returns: function* gen() { yield 1; yield 2; yield 3; } const g = gen(); // "generator { }" g.next(); // "object { value: 1, done: false }" g.next(); // "object { value: 2, done: false }" g.next(); // "object { value: 3, done: false }" g.next(); // "object { value: undefined, done: true }" using next() with a list function* getpage(pagesize = 1, list) { let output = []; let index = 0; while (index < list.length) { output = []; for (let i = index; i < index + pagesize; i++) { if (list[i]) { ...
... output.push(list[i]); } } yield output; index += pagesize; } } list = [1, 2, 3, 4, 5, 6, 7, 8] var page = getpage(3, list); // generator { } page.next(); // object {value: (3) [1, 2, 3], done: false} page.next(); // object {value: (3) [4, 5, 6], done: false} page.next(); // object {value: (2) [7, 8], done: false} page.next(); // object {value: undefined, done: true} sending values to the generator in this example, next is called with a value.
... function* gen() { while (true) { let value = yield null; console.log(value); } } const g = gen(); g.next(1); // "{ value: null, done: false }" g.next(2); // 2 // "{ value: null, done: false }" specifications specification ecmascript (ecma-262)the definition of 'generator.prototype.next' in that specification.

Intl.Locale.prototype.numeric - JavaScript
numeric is a boolean value, which means that it can be either true or false.
... if numeric is set to false, there will be no special handling of numeric values in strings.
...to set the value to false, you must specify in by adding "false" after the kn key.
... let numericviastr = new intl.locale("fr-latn-fr-u-kn-false"); console.log(numericstr.numeric); // prints "false" setting the numeric value via the configuration object argument the intl.locale constructor has an optional configuration object argument, which can be used to pass extension types.

Object.defineProperties() - JavaScript
defaults to false.
... defaults to false.
... defaults to false.
...eys.length; i++) descs.push([keys[i], converttodescriptor(properties[keys[i]])]); for (var i = 0; i < descs.length; i++) object.defineproperty(obj, descs[i][0], descs[i][1]); return obj; } examples using object.defineproperties var obj = {}; object.defineproperties(obj, { 'property1': { value: true, writable: true }, 'property2': { value: 'hello', writable: false } // etc.

Object.prototype.propertyIsEnumerable() - JavaScript
if the object does not have the specified property, this method returns false.
...built-in properties: var a = ['is enumerable']; a.propertyisenumerable(0); // returns true a.propertyisenumerable('length'); // returns false math.propertyisenumerable('random'); // returns false this.propertyisenumerable('math'); // returns false direct vs.
... inherited properties var a = []; a.propertyisenumerable('constructor'); // returns false function firstconstructor() { this.property = 'is not enumerable'; } firstconstructor.prototype.firstmethod = function() {}; function secondconstructor() { this.method = function() { return 'is enumerable'; }; } secondconstructor.prototype = new firstconstructor; secondconstructor.prototype.constructor = secondconstructor; var o = new secondconstructor(); o.arbitraryproperty = 'is enumerable'; o.propertyisenumerable('arbitraryproperty'); // returns true o.propertyisenumerable('method'); // returns true o.propertyisenumerable('property'); // returns false o.property = 'is enumerable'; o.propertyisenumerable('property'); // returns true // these retu...
...rn false as they are on the prototype which // propertyisenumerable does not consider (even though the last two // are iteratable with for-in) o.propertyisenumerable('prototype'); // returns false (as of js 1.8.1/ff3.6) o.propertyisenumerable('constructor'); // returns false o.propertyisenumerable('firstmethod'); // returns false specifications specification ecmascript (ecma-262)the definition of 'object.prototype.propertyisenumerable' in that specification.

handler.setPrototypeOf() - JavaScript
return value the setprototypeof() method returns true if the [[prototype]] was successfully changed, otherwise false.
... examples if you want to disallow setting a new prototype for your object, your handler's setprototypeof() method can either return false, or it can throw an exception.
... approach 1: returning false this approach means that any mutating operation that throws an exception on failure to mutate, must create the exception itself.
... const handlerreturnsfalse = { setprototypeof(target, newproto) { return false; } }; const newproto = {}, target = {}; const p1 = new proxy(target, handlerreturnsfalse); object.setprototypeof(p1, newproto); // throws a typeerror reflect.setprototypeof(p1, newproto); // returns false approach 2: throwing an exception the latter approach will cause any operation that attempts to mutate, to throw.

Reflect.isExtensible() - JavaScript
reflect.preventextensions(empty) reflect.isextensible(empty) // === false // sealed objects are by definition non-extensible.
... let sealed = object.seal({}) reflect.isextensible(sealed) // === false // frozen objects are also by definition non-extensible.
... let frozen = object.freeze({}) reflect.isextensible(frozen) // === false difference to object.isextensible() if the target argument to this method is not an object (a primitive), then it will cause a typeerror.
... reflect.isextensible(1) // typeerror: 1 is not an object object.isextensible(1) // false specifications specification ecmascript (ecma-262)the definition of 'reflect.isextensible' in that specification.

Reflect.setPrototypeOf() - JavaScript
it sets the prototype (i.e., the internal [[prototype]] property) of a specified object to another object or to null, and returns true if the operation was successful, or false otherwise.
...reflect.setprototypeof({}, null) // true // returns false if target is not extensible.
... reflect.setprototypeof(object.freeze({}), null) // false // returns false if it cause a prototype chain cycle.
... let target = {} let proto = object.create(target) reflect.setprototypeof(target, proto) // false specifications specification ecmascript (ecma-262)the definition of 'reflect.setprototypeof' in that specification.

RegExp.prototype.test() - JavaScript
returns true or false.
...otherwise, false.
... when test() returns false, the calling regex's lastindex property will reset to 0.
... the following example demonstrates this behaviour: const regex = /foo/g; // the "global" flag is set // regex.lastindex is at 0 regex.test('foo') // true // regex.lastindex is now at 3 regex.test('foo') // false // regex.lastindex is at 0 regex.test('barfoo') // true // regex.lastindex is at 6 regex.test('foobar') //false // regex.lastindex is at 0 // (...and so on) specifications specification ecmascript (ecma-262)the definition of 'regexp.test' in that specification.

String.prototype.includes() - JavaScript
the includes() method determines whether one string may be found within another string, returning true or false as appropriate.
...(defaults to 0.) return value true if the search string is found anywhere within the given string; otherwise, false if not.
...for example, the following expression returns false: 'blue whale'.includes('blue') // returns false polyfill this method has been added to the ecmascript 2015 specification and may not be available in all javascript implementations yet.
... throw typeerror('first argument must not be a regexp'); } if (start === undefined) { start = 0; } return this.indexof(search, start) !== -1; }; } examples using includes() const str = 'to be, or not to be, that is the question.' console.log(str.includes('to be')) // true console.log(str.includes('question')) // true console.log(str.includes('nonexistent')) // false console.log(str.includes('to be', 1)) // false console.log(str.includes('to be')) // false console.log(str.includes('')) // true specifications specification ecmascript (ecma-262)the definition of 'string.prototype.includes' in that specification.

TypedArray.prototype.some() - JavaScript
return value true if the callback function returns a truthy value for any array element; otherwise, false.
...otherwise, some returns false.
... function isbiggerthan10(element, index, array) { return element > 10; } new uint8array([2, 5, 8, 1, 4]).some(isbiggerthan10); // false new uint8array([12, 5, 8, 1, 4]).some(isbiggerthan10); // true testing typed array elements using arrow functions arrow functions provide a shorter syntax for the same test.
... new uint8array([2, 5, 8, 1, 4]).some(elem => elem > 10); // false new uint8array([12, 5, 8, 1, 4]).some(elem => elem > 10); // true specifications specification ecmascript (ecma-262)the definition of 'typedarray.prototype.some' in that specification.

Conditional (ternary) operator - JavaScript
expriftrue : expriffalse parameters condition an expression whose value is used as a condition.
... expriffalse an expression which is executed if the condition is falsy (that is, has a value which can be converted to false).
... description besides false, possible falsy expressions are: null, nan, 0, the empty string (""), and undefined.
... if condition is any of these, the result of the conditional expression will be the result of executing the expression expriffalse.

<mtable> - MathML
note: the <mtable> element resets the displaystyle attribute to false.
... displaystyle a boolean value specifying whether more vertical space is used for displayed equations or, if set to false, a more compact layout is used to display formulas.
...false is default.
...false is default.

Autoplay guide for media and Web Audio APIs - Web media technologies
this is currently false by default (except in nightly builds, where it's true by default).
... if this is false, the allowedtoplay property is missing from the htmlmediaelement interface, and is thus not present on either <audio> or <video> elements.
...setting this value to false disables this capability.
...if this has been changed to false, media with an audio track will not be permitted to play even if muted.

boolean - XPath
xslt/xpath reference: xslt elements, exslt functions, xpath functions, xpath axes the boolean function evaluates an expression and returns true or false.
... returns boolean true or false after evaluating expression.
... notes a number evaluates to false if it is positive or negative zero or nan.
... a string evaluates to false if it an empty string.

Communicating using "postMessage" - Archive of obsolete content
el").panel({ onmessage: function(contentscriptmessage) { // handle message from the content script } }); message events versus user-defined events you can use message events as an alternative to user-defined events: var pagemodscript = "window.addeventlistener('mouseover', function(event) {" + " self.postmessage(event.target.tostring());" + "}, false);"; var pagemod = require('sdk/page-mod').pagemod({ include: ['*'], contentscript: pagemodscript, onattach: function(worker) { worker.on('message', function(message) { console.log('mouseover: ' + message); }); } }); the reason to prefer user-defined events is that as soon as you need to send more than one type of message, then both sending and receiving messages gets more...
... the event type in the message payload, and implement a switch function in the receiver to dispatch the message: var pagemodscript = "window.addeventlistener('mouseover', function(event) {" + " self.postmessage({" + " kind: 'mouseover'," + " element: event.target.tostring()" + " });" + "}, false);" + "window.addeventlistener('mouseout', function(event) {" + " self.postmessage({" + " kind: 'mouseout'," + " element: event.target.tostring()" + " });" + " }, false);" var pagemod = require('sdk/page-mod').pagemod({ include: ['*'], contentscript: pagemodscript, ...
... break; case 'mouseout': console.log('mouseout: ' + message.element); break; } }); } }); implementing the same add-on with user-defined events is shorter and more readable: var pagemodscript = "window.addeventlistener('mouseover', function(event) {" + " self.port.emit('mouseover', event.target.tostring());" + "}, false);" + "window.addeventlistener('mouseout', function(event) {" + " self.port.emit('mouseout', event.target.tostring());" + "}, false);"; var pagemod = require('sdk/page-mod').pagemod({ include: ['*'], contentscript: pagemodscript, onattach: function(worker) { worker.port.on('mouseover', function(message) { console.log('mo...

frame/utils - Archive of obsolete content
defaults to false.
...defaults to false.
...defaults to false.

system/events - Archive of obsolete content
var events = require("sdk/system/events"); var { ci } = require("chrome"); function listener(event) { var channel = event.subject.queryinterface(ci.nsihttpchannel); channel.setrequestheader("user-agent", "mybrowser/1.0", false); } events.on("http-on-modify-request", listener); globals functions emit(type, event) send an event to observer service parameters type : string the event type.
...this object has three attributes: type: the event type name subject: the event subject object data: the event data string strong : boolean default is false, a weak reference, which means it can be garbage collected at any time if there are no other references to it.
... strong : boolean default is false, a weak reference, which means it can be garbage collected at any time if there are no other references to it.

system/xul-app - Archive of obsolete content
returns boolean : true if the host application is name and false otherwise.
... returns boolean : true if the host application is one of the names and false otherwise.
... returns boolean : true if version falls in the given range and false otherwise.

ui/button/toggle - Archive of obsolete content
y button", icon: { "16": "./icon-16.png", "32": "./icon-32.png", "64": "./icon-64.png" }, onchange: handlechange }); var panel = panels.panel({ contenturl: self.data.url("panel.html"), onhide: handlehide }); function handlechange(state) { if (state.checked) { panel.show({ position: button }); } } function handlehide() { button.state('window', {checked: false}); } disabling buttons you can disable a button by setting its disabled property to true.
...defaults to false.
...it's initialized to false, or the value of the checked option to the button's constructor.

Creating Event Targets - Archive of obsolete content
d: function(aitemid, afolder, aindex) { console.log("added ", bookmarkservice.getbookmarkuri(aitemid).spec); }, onitemvisited: function(aitemid, avisitid, time) { console.log("visited ", bookmarkservice.getbookmarkuri(aitemid).spec); }, queryinterface: xpcomutils.generateqi([ci.nsinavbookmarkobserver]) }; exports.main = function() { bookmarkservice.addobserver(bookmarkobserver, false); }; exports.onunload = function() { bookmarkservice.removeobserver(bookmarkobserver); } try running this add-on, adding and visiting bookmarks, and observing the output in the console.
...arkobserver = { onitemadded: function(aitemid, afolder, aindex) { emit(exports, "added", bookmarkservice.getbookmarkuri(aitemid).spec); }, onitemvisited: function(aitemid, avisitid, time) { emit(exports, "visited", bookmarkservice.getbookmarkuri(aitemid).spec); }, queryinterface: xpcomutils.generateqi([ci.nsinavbookmarkobserver]) }; bookmarkservice.addobserver(bookmarkobserver, false); exports.on = on.bind(null, exports); exports.once = once.bind(null, exports); exports.removelistener = function removelistener(type, listener) { off(exports, type, listener); }; this code implements a module which can emit added and visited events.
...temadded: function(aitemid, afolder, aindex) { emit(target, "added", bookmarkservice.getbookmarkuri(aitemid).spec); }, onitemvisited: function(aitemid, avisitid, time) { emit(target, "visited", bookmarkservice.getbookmarkuri(aitemid).spec); }, queryinterface: xpcomutils.generateqi([ci.nsinavbookmarkobserver]) }; bookmarkservice.addobserver(bookmarkobserver, false); } var bookmarkmanager = class({ extends: eventtarget, initialize: function initialize(options) { eventtarget.prototype.initialize.call(this, options); merge(this, options); createobserver(this); } }); exports.bookmarkmanager = bookmarkmanager; the code to interact with the places api is the same here.

Creating Reusable Modules - Archive of obsolete content
.createinstance(ci.nsifileinputstream); // open for reading istream.init(f, 0x01, 0444, 0); var ch = cc["@mozilla.org/security/hash;1"] .createinstance(ci.nsicryptohash); // we want to use the md5 algorithm ch.init(ch.md5); // this tells updatefromstream to read the entire file const pr_uint32_max = 0xffffffff; ch.updatefromstream(istream, pr_uint32_max); // pass false here to get binary data back var hash = ch.finish(false); // convert the binary hash data to a hex string.
... .createinstance(ci.nsifileinputstream); // open for reading istream.init(f, 0x01, 0444, 0); var ch = cc["@mozilla.org/security/hash;1"] .createinstance(ci.nsicryptohash); // we want to use the md5 algorithm ch.init(ch.md5); // this tells updatefromstream to read the entire file const pr_uint32_max = 0xffffffff; ch.updatefromstream(istream, pr_uint32_max); // pass false here to get binary data back var hash = ch.finish(false); // convert the binary hash data to a hex string.
... .createinstance(ci.nsifileinputstream); // open for reading istream.init(f, 0x01, 0444, 0); var ch = cc["@mozilla.org/security/hash;1"] .createinstance(ci.nsicryptohash); // we want to use the md5 algorithm ch.init(ch.md5); // this tells updatefromstream to read the entire file const pr_uint32_max = 0xffffffff; ch.updatefromstream(istream, pr_uint32_max); // pass false here to get binary data back var hash = ch.finish(false); // convert the binary hash data to a hex string.

Displaying web content in an extension without security issues - Archive of obsolete content
so in the simplest case you would have: <iframe type="content" src="data:text/html,%3chtml%3e%3cbody%3e%3c/body%3e%3c/html%3e"/> but usually you don’t want to start with an empty document, you would rather want to load some template into the frame: var request = new xmlhttprequest(); request.open("get", "chrome://foo/content/template.html", false); request.send(null); frame.setattribute("src", "data:text/html," + encodeuricomponent(request.responsetext)); that way you can have the template in your extension but still strip it off all privileges when it is loaded in a frame.
...it won’t harm disabling everything else as well unless it is really required: frame.docshell.allowauth = false; frame.docshell.allowimages = false; frame.docshell.allowjavascript = false; frame.docshell.allowmetaredirects = false; frame.docshell.allowplugins = false; frame.docshell.allowsubframes = false; but what about interactivity, for example if you want a certain reaction to mouse clicks?
...instead, nsiscriptableunescapehtml.parsefragment() method should be used that is meant for just that scenario: var target = entry.getelementsbyclassname("description")[0]; var fragment = components.classes["@mozilla.org/feed-unescapehtml;1"] .getservice(components.interfaces.nsiscriptableunescapehtml) .parsefragment(description, false, null, target); target.appendchild(fragment); this will add the html code to the specified node — minus all the potentially dangerous content.

Installing Extensions and Themes From Web Pages - Archive of obsolete content
/javascript"> <!-- function install (aevent) { for (var a = aevent.target; a.href === undefined;) a = a.parentnode; var params = { "foo": { url: aevent.target.href, iconurl: aevent.target.getattribute("iconurl"), hash: aevent.target.getattribute("hash"), tostring: function () { return this.url; } } }; installtrigger.install(params); return false; } //--> </script> <a href="http://www.example.com/foo.xpi" iconurl="http://www.example.com/foo.png" hash="sha1:28857e60d043447c5f4550853f2d40770b326a13" onclick="return install(event);">install extension!</a> let's go through this piece by piece.
... return false; this last part is the most important - the install function must return false so that when the link is clicked, only the script is run, and the link href is not navigated to.
...and your site is not in the whitelist, when the user invokes that code, updateenabled will return false because your site isn't whitelisted, and since it was updateenabled that discovered this, not a call to install, there will be no notification to the user.

Appendix B: Install and Uninstall Scripts - Archive of obsolete content
window.addeventlistener( "load", function() { xulschoolchrome.browseroverlay.init(); }, false); then all we need is some persistent flag that ensures that the first run code is only run once.
...so, if we were to use fuel, we can do the following in the init function: init : function() { let firstrunpref = "extensions.xulschoolhello.firstrundone"; if (!application.prefs.getvalue(firstrunpref, false)) { application.prefs.setvalue(firstrunpref, true); // all the rest of the first run code goes here.
... } } in this case you would need to declare the first run preference in your default preferences file, with a default value of false.

Appendix D: Loading Scripts - Archive of obsolete content
this behavior can be reversed by setting the wantsxrays parameter to false when constructing the sandbox.
... const xmlhttprequest = components.constructor("@mozilla.org/xmlextras/xmlhttprequest;1", "nsixmlhttprequest", "open"); function loadscript(name, context) { // create the sandbox let sandbox = components.utils.sandbox(context, { sandboxprototype: context, wantxrays: false }); // get the caller's filename let file = components.caller.stack.filename; // strip off any prefixes added by the sub-script loader // and the trailing filename let directory = file.replace(/.* -> |[^\/]+$/g, ""); let scriptname = directory + name; // read the script let xmlhttp = xmlhttprequest("get", scriptname, false); xmlhttp.overridemimetype("text...
... function loadscript(name, context) { // create the sandbox let sandbox = components.utils.sandbox(context, { sandboxprototype: context, wantxrays: false }); // get the caller's filename let file = components.caller.stack.filename; // strip off any prefixes added by the sub-script loader // and the trailing filename let directory = file.replace(/.* -> |[^\/]+$/g, ""); services.scriptloader.loadsubscript(directory + name, sandbox, "utf-8"); } loadscript("foo.js", this); javasc...

Appendix F: Monitoring DOM changes - Archive of obsolete content
; } to { clip: rect(0px, auto, auto, auto); } \n\ }\n'; let properties = [ 'animation-duration: 0.0001s;', 'animation-name: ' + event + ' !important;' ]; properties = properties.map(function (prop) ' ' + watchnodes.namespace + prop) .join('\n'); doc.addeventlistener('animationstart', listener, false); function listener(event) { if (event.animationname == event) callback.call(this, event); } style.textcontent = ' ' + preamble + selector + '{' + properties + '}'; (doc.head || doc.documentelement).appendchild(style); // this will only work in chrome privileged code.
... style = components.utils.getweakreference(style); return function unwatch() { if (style.get()) { style.get().ownerdocument.removeeventlistener('animationstart', listener, false); style.get().parentnode.removechild(style.get()); } }; } watchnodes.namespace = 'mozcsskeyframerule' in window ?
... '-moz-' : ''; watchnodes.prefix = 'keyframe-node-inserted-' + math.floor(math.random() + 0xffffffff) + '-'; watchnodes._i = 0; } else { watchnodes = function watchnodes(selector, callback, doc) { doc = doc || document; doc.addeventlistener('domnodeinserted', listener, false); function listener(event) { if (event.target.mozmatchesselector(selector)) callback.call(this, event); } return function unwatch() { doc.removeeventlistener('domnodeinserted', listener, false); }; } } xbl xbl is similar in approach to the above animation-based method.

JavaScript Client API - Archive of obsolete content
itemexists(guid) should simply return true if an item with the given guid exists in the store, false otherwise.
...it's a bit smarter to have // yourself notified when to start and stop tracking therefore: svc.obs.add("weave:engine:start-tracking", this); svc.obs.add("weave:engine:stop-tracking", this); } footracker.prototype = { __proto__: tracker.prototype, _enabled: false, observe: function observe(subject, topic, data) { switch (topic) { case "weave:engine:start-tracking": if (!this._enabled) { // register event handler or observer here ...
... this._enabled = false; } break; }, onevent: function onevent() { /* here is where you'd handle the event.

JavaScript crypto - Archive of obsolete content
<script> function onsmartcardchange() { window.location.reload(); } function register() { window.crypto.enablesmartcardevents = true; document.addeventlistener("smartcard-insert", onsmartcardchange, false); document.addeventlistener("smartcard-remove", onsmartcardchange, false); } function deregister() { document.removeeventlistener("smartcard-insert", onsmartcardchange, false); document.removeeventlistener("smartcard-remove", onsmartcardchange, false); } document.body.onload = register; document.body.onunload = deregister; </script> with the above example, your web site will automaticall...
... if (typeof(crypto.version) != "undefined") { crmfobject = crypto.generatecrmfrequest( "cn=" + form.name.value, form.password.value, authenticator, keytransportcert, "setcrmfrequest();", 1024, null, "rsa-dual-use"); } return false; } function setcrmfrequest() { form.cert_request.value = crmfobject.request; form.submit(); } form.onsubmit = validate; </script> on completion of the request, the ca may submit a page that looks something like this: <!doctype html> <h2>certificate request successful</h2> <p>hit 'load' to load your certificate</p> <form name="reqform"> <p><input type=submit name="load" value="submit"></p...
...> </form> <script> /* the following values could be filled in by the server cgi */ var nickname= "mycertnickname"; var cert = "mkjflakdjfiwjflaksufklasf ..."; var forcebackup = false; function loadcertificate() { window.crypto.importusercertificates(nickname, cert, forcebackup); return false; } document.forms[0].onsubmit = loadcertificate; </script> signing text domstring signtext(domstring stringtosign, domstring caoption /* ...

Supporting private browsing mode - Archive of obsolete content
function privatebrowsinglistener() { this.init(); } privatebrowsinglistener.prototype = { _os: null, _inprivatebrowsing: false, // whether we are in private browsing mode _watcher: null, // the watcher object init : function () { this._inited = true; this._os = components.classes["@mozilla.org/observer-service;1"] .getservice(components.interfaces.nsiobserverservice); this._os.addobserver(this, "private-browsing", false); this._os.addobserver(this, "quit-application", false);...
...ons of firefox } }, observe : function (asubject, atopic, adata) { if (atopic == "private-browsing") { if (adata == "enter") { this._inprivatebrowsing = true; if (this.watcher && "onenterprivatebrowsing" in this._watcher) { this.watcher.onenterprivatebrowsing(); } } else if (adata == "exit") { this._inprivatebrowsing = false; if (this.watcher && "onexitprivatebrowsing" in this._watcher) { this.watcher.onexitprivatebrowsing(); } } } else if (atopic == "quit-application") { this._os.removeobserver(this, "quit-application"); this._os.removeobserver(this, "private-browsing"); } }, get inprivatebrowsing() { return this._inprivatebrowsing; }, get...
... asubject.queryinterface(components.interfaces.nsisupportsprbool); // if another extension has not already canceled entering the private mode if (!asubject.data) { if (adata == "exit") { // if we are leaving the private mode /* you should display some user interface here */ asubject.data = true; // cancel the operation } } }, "private-browsing-cancel-vote", false); note: a well-mannered extension should display some sort of user interface to indicate that private browsing mode will be kept on, and possibly offer the option to cancel whatever operation is preventing the extension from allowing private browsing to be shut off.

Elements - Archive of obsolete content
field <!element field empty> <!attlist field id id #implied name cdata #required readonly (true|false) #implied > a field is similar to a property, except that it should not have a getter or setter.
... property <!entity % property-content "(getter?,setter?)"> <!element property %property-content;> <!attlist property id id #implied name cdata #required readonly (true|false) #implied onget cdata #implied onset cdata #implied > the property element represents a single property of an implementation.
...rs cdata #implied keycode cdata #implied key cdata #implied charcode cdata #implied clickcount (1|2|3) #implied command id #implied preventdefault false|true #implied > the handler element describes a single event handler.

spellcheck - Archive of obsolete content
« xul reference home spellcheck type: boolean if true, spell checking is enabled by default for the text box; if false, spell checking is disabled by default.
... if not specified, this defaults to false the html the spellcheck attribute uses values of true or false (you cannot simply add the spellcheck attribute to a given element): <!-- spellcheck everything!
...--> <input type="text" spellcheck="false" /><br /> <textarea spellcheck="false"></textarea> <div contenteditable="true" spellcheck="false">i am some content</div> you can use spellcheck on input, textarea, and contenteditable elements.

Tree Widget Changes - Archive of obsolete content
this will be hidden if the column redordering is disabled using enablecolumndrag="false".
...when the user clicks the cell, the view's setcellvalue method will be called with either the value true or false.
...in this case, disable editing for that cell by setting editable to false for that cell, as in the following: <treecell value="true" editable="false"/> or, for custom views, return false from the iseditable method.

Modifying a XUL Interface - Archive of obsolete content
if false, only the node is copied, such that the copy won't have any children.
...note that while the label and value properties are strings, the checked property is a boolean property which will be set either true or false.
... note: if you're creating the checkbox dynamically and it's not yet added to the dom, you must use setattribute("checked", "false") instead, because the xbl isn't initiated yet.) example 6 : source view <button label="change" oncommand="this.nextsibling.checked = !this.nextsibling.checked;"/> <checkbox label="check for messages"/> radio buttons may be selected as well using properties, however since only one in a group may be selected at a time, the others must all be unchecked when one is checked.

XUL Questions and Answers - Archive of obsolete content
specifying window.onload function to specify a function to run when the window is loaded,add the following code between the script tags in the xul file: window.addeventlistener("load", function(e) { startup(); }, false); similarly, for onunload use the code: window.addeventlistener("unload", function(e) { shutdown(); }, false); is there an event which is called when the firefox browser is initialized?
... instead of <menulist id="abpopup"> <menupopup id="abpopup-menupopup" ref="moz-abdirectory://" datasources="rdf:addressdirectory" sortactive="true" sortdirection="ascending" sortresource="http://home.netscape.com/nc-rdf#dirtreenamesort"> <template> <rule nc:iswriteable="false"/> <rule nc:ismaillist="false"> <menuitem uri="..." label="rdf:http://home.netscape.com/nc-rdf#dirname" value="rdf:http://home.netscape.com/nc-rdf#diruri"/> </rule> <rule nc:ismaillist="true"> <menuitem uri="..." label="rdf:http://home.netscape.com/nc-rdf#dirname" value="rdf:http://home.netscape.com/nc-rdf#diruri"/> <...
.../rule> </template> </menupopup> </menulist> it should be written as follows: <menulist id="abpopup22"> <menupopup id="abpopup-menupopup" ref="moz-abmdbdirectory://abook.mab" datasources="rdf:addressdirectory" sortactive="true" sortdirection="ascending" sortresource="http://home.netscape.com/nc-rdf#dirtreenamesort"> <template> <rule nc:iswriteable="false"/> <rule nc:ismaillist="true"> <menuitem uri="..." label="rdf:http://home.netscape.com/nc-rdf#dirname" value="rdf:http://home.netscape.com/nc-rdf#diruri"/> </rule> </template> </menupopup> </menulist> drawwindow with transparent background possible?

arrowscrollbox - Archive of obsolete content
if false, the mouse must be hovered over the arrows to scroll automatically.
...do not set the attribute to true, as this will suggest you can set it to false to enable the element again, which is not the case.
... smoothscroll type: boolean true initially enables smooth scrolling for the corresponding arrowscrollbox, false disables it.

button - Archive of obsolete content
if this attribute is false, the checked state must be adjusted manually.
...if you wish to have different behavior for how the states are adjusted, set the autocheck attribute to false and adjust the state with a script.
...do not set the attribute to true, as this will suggest you can set it to false to enable the element again, which is not the case.

menu - Archive of obsolete content
do not set the attribute to true, as this will suggest you can set it to false to enable the element again, which is not the case.
...the menu may be opened by setting the open property to true and closed by setting it to false.
... selected type: boolean this property's value is true if this element is selected, or false if it is not.

menupopup - Archive of obsolete content
returning false from this event handler prevents the popup from appearing.
... iscontextmenu the iscontextmenu argument should be true for context menus and false for all other types of popups.
...if attributesoverride is false, the attribute is only used if the position argument is empty.

preference - Archive of obsolete content
do not set the attribute to true, as this will suggest you can set it to false to enable the element again, which is not the case.
... bool a boolean set to either true or false.
... there's a special case of value === undefined, indicating that the preference does not have a user-set value (hasuservalue == false).

toolbar - Archive of obsolete content
when set to false, the default, the toolbar is visible.
...when set to false, the default, the grippy will be shown.
...otherwise, if the beforepermanent argument is false, the new item is added to the end of the toolbar.

toolbarbutton - Archive of obsolete content
if this attribute is false, the checked state must be adjusted manually.
...if you wish to have different behavior for how the states are adjusted, set the autocheck attribute to false and adjust the state with a script.
...do not set the attribute to true, as this will suggest you can set it to false to enable the element again, which is not the case.

treecol - Archive of obsolete content
<tree flex="1" editable="true"> <treecols> <treecol label="active" type="checkbox" editable="true"/> <treecol label="name" flex="1" /> </treecols> <treechildren> <treeitem> <treerow> <treecell value="true"/> <treecell label="alice"/> </treerow> </treeitem> <treeitem> <treerow> <treecell value="false"/> <treecell label="bob"/> </treerow> </treeitem> </treechildren> </tree> to make the checkbox visible on some platforms, the following styles need to be added to the stylesheet (see treecol.type).
...individual treecell elements in the column may be marked editable="false" in order to disable editing.
...if false or not specified, the user can adjust the size of the column, typically by dragging the column header with the mouse.

CommandLine - Archive of obsolete content
an nsicommandline object is passed as the first argument of the launched window: example var cmdline = window.arguments[0]; cmdline = cmdline.queryinterface(components.interfaces.nsicommandline); alert(cmdline.handleflagwithparam("test", false)); see also: chrome: command line for single instance applications of course, for a single instance application (see toolkit.singletonwindowtype for more information), the last example still applies the first time your application is launched.
...spec) { return apphandlermodule; } create an observer that will get notified when arguments change: chrome/content/cmdline.js function commandlineobserver() { this.register(); } commandlineobserver.prototype = { observe: function(asubject, atopic, adata) { var cmdline = asubject.queryinterface(components.interfaces.nsicommandline); var test = cmdline.handleflagwithparam("test", false); alert("test = " + test); }, register: function() { var observerservice = components.classes["@mozilla.org/observer-service;1"] .getservice(components.interfaces.nsiobserverservice); observerservice.addobserver(this, "commandline-args-changed", false); }, unregister: function() { var observerservice = components.classes["@mozilla.org...
...var observerservice = components.classes["@mozilla.org/observer-service;1"] .getservice(components.interfaces.nsiobserverservice); observerservice.notifyobservers(window.arguments[0], "commandline-args-changed", null); addeventlistener("unload", observer.unregister, false); finally, add a reference in your application window to the observer: chrome/content/window.xul <?xml version="1.0"?> <?xml-stylesheet href="chrome://global/skin/" type="text/css"?> <window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" id="main" title="&window.title;" windowtype="xulmine" style="width: 300px; height: 350px;" persist="screenx sc...

XULRunner tips - Archive of obsolete content
s.xul?type=themes"); pref("xpinstall.dialog.progress.chrome", "chrome://mozapps/content/extensions/extensions.xul?type=extensions"); pref("xpinstall.dialog.progress.type.skin", "extension:manager-themes"); pref("xpinstall.dialog.progress.type.chrome", "extension:manager-extensions"); pref("extensions.update.enabled", true); pref("extensions.update.interval", 86400); pref("extensions.dss.enabled", false); pref("extensions.dss.switchpending", false); pref("extensions.ignoremtimechanges", false); pref("extensions.logging.enabled", false); pref("general.skins.selectedskin", "classic/1.0"); // nb these point at amo pref("extensions.update.url", "chrome://mozapps/locale/extensions/extensions.properties"); pref("extensions.getmoreextensionsurl", "chrome://mozapps/locale/extensions/extensions.propertie...
...anager.showalertoncomplete", true); pref("browser.download.manager.showalertinterval", 2000); pref("browser.download.manager.retention", 2); pref("browser.download.manager.showwhenstarting", true); pref("browser.download.manager.usewindow", true); pref("browser.download.manager.closewhendone", true); pref("browser.download.manager.opendelay", 0); pref("browser.download.manager.focuswhenstarting", false); pref("browser.download.manager.flashcount", 2); // pref("alerts.slideincrement", 1); pref("alerts.slideincrementtime", 10); pref("alerts.totalopentime", 4000); pref("alerts.height", 50); if you are missing preferences that a dialog requires, you will get the following errors: component returned failure code: 0x8000ffff (ns_error_unexpected) [nsiprefbranch.getboolpref] error: dialog has no p...
... pref("signon.remembersignons", true); pref("signon.expiremasterpassword", false); pref("signon.signonfilename", "signons.txt"); you also need to get an instance of the login manager service, which internally initializes the system: components.classes["@mozilla.org/login-manager;1"].getservice(components.interfaces.nsiloginmanager); using firefox to run xulrunner applications firefox 3 and up contain the xulrunner runtime.

NPEvent - Archive of obsolete content
values: 0 nullevent 1 mousedown 2 mouseup 3 keydown 4 keyup 5 autokey 6 updateevt 7 diskevt 8 activateevt 15 osevt 23 khighlevelevent getfocusevent 0, 1 (true, false) losefocusevent adjustcursorevent 0, 1 (true, false) for information about these events, see the mac os developer documentation.
... if your plug-in ignores key events, return false, and the key events will be processed by the browser itself.
... if you don't want a special cursor, return false and the browser will use the standard arrow cursor.

The global XML object - Archive of obsolete content
observe: var element = <foo> <!-- my comment --> <bar/> </foo>; element.comments().length(); // returns 0 element.toxmlstring(); // returns <foo><bar/></foo> xml.ignorecomments = false; element = <foo> <!-- my comment --> <bar/> </foo>; element.comments().length(); // returns 1 element.toxmlstring(); // returns <foo><!-- my comment --><bar/></foo> ignoreprocessinginstructions true by default.
...for example var element = <foo> <?process x="true"?> <bar/> <?process x="false"?> </foo>; element.toxmlstring(); // returns <foo><bar/></foo> xml.ignoreprocessinginstructions = false; var element = <foo> <?process x="true"?> <bar/> <?process x="false"?> </foo>; element.toxmlstring(); // returns <foo><?process x="true"?><bar/><?process x="false"?></foo> ignorewhitespace true by default.
...ignored if prettyprinting is false.

Desktop mouse and keyboard controls - Game development
first, we'd need an event listener to listen for the pressed keys: document.addeventlistener('keydown', keydownhandler, false); document.addeventlistener('keyup', keyuphandler, false); whenever any key is pressed down, we're executing the keydownhandler function, and when press finishes we're executing the keyuphandler function, so we know when it's no longer pressed.
... to do that we'll hold the information on whether the keys we are interested in are pressed or not: var rightpressed = false; var leftpressed = false; var uppressed = false; var downpressed = false; then we will listen for the keydown and keyup events and act accordingly in both handler functions.
...keycode == 39) { rightpressed = true; } else if(event.keycode == 37) { leftpressed = true; } if(event.keycode == 40) { downpressed = true; } else if(event.keycode == 38) { uppressed = true; } } the keyuphandler looks almost exactly the same as the keydownhandler above, but instead of setting the pressed variables to true, we would set them to false.

Falsy - MDN Web Docs Glossary: Definitions of Web-related terms
a falsy (sometimes written falsey) value is a value that is considered false when encountered in a boolean context.
... there are 8 falsy values: false the keyword false 0 the number zero -0 the number negative zero 0n bigint, when used as a boolean, follows the same rule as a number.
... examples examples of falsy values in javascript (which are coerced to false in boolean contexts, and thus bypass the if block): if (false) if (null) if (undefined) if (0) if (-0) if (0n) if (nan) if ("") the logical and operator, && if the first object is falsy, it returns that object false && "dog" // ↪ false 0 && "dog" // ↪ 0 specifications specification ecmascript (ecma-262)the definition of 'toboolean abstract operation' in that spe...

WAI-ARIA basics - Learn web development
when this is checked/unchecked, we update the text inside the hidden live region to tell screenreader users what the result of checking this checkbox is, as well as updating the aria-disabled state, and some visual indicators too: function togglemusician(bool) { let instruitem = formitems[formitems.length-1]; if(bool) { instruitem.input.disabled = false; instruitem.label.style.color = '#000'; instruitem.input.setattribute('aria-disabled', 'false'); hiddenalert.textcontent = 'instruments played field now enabled; use it to tell us what you play.'; } else { instruitem.input.disabled = true; instruitem.label.style.color = '#999'; instruitem.input.setattribute('aria-disabled', 'true'); instruitem.input.removeattribute('...
...we've updated the structure of the tabbed interface like so: <ul role="tablist"> <li class="active" role="tab" aria-selected="true" aria-setsize="3" aria-posinset="1" tabindex="0">tab 1</li> <li role="tab" aria-selected="false" aria-setsize="3" aria-posinset="2" tabindex="0">tab 2</li> <li role="tab" aria-selected="false" aria-setsize="3" aria-posinset="3" tabindex="0">tab 3</li> </ul> <div class="panels"> <article class="active-panel" role="tabpanel" aria-hidden="false"> ...
...in addition, because of the aria-hidden settings (only the non-hidden tab ever has aria-hidden="false" set), the non-hidden content is the only one you can navigate down to, meaning the selected content is easier to find.

Client-side storage - Learn web development
if it has been stored, this call will evaluate to true; if not, it will be false.
...if it is false, we display a generic greeting and do the opposite.
... // grab a reference to the opened database let db = e.target.result; // create an objectstore to store our notes in (basically like a single table) // including a auto-incrementing key let objectstore = db.createobjectstore('notes_os', { keypath: 'id', autoincrement:true }); // define what data items the objectstore will contain objectstore.createindex('title', 'title', { unique: false }); objectstore.createindex('body', 'body', { unique: false }); console.log('database setup complete'); }; this is where we define the schema (structure) of our database; that is, the set of columns (or fields) it contains.

Client-Server Overview - Learn web development
chrome/52.0.2743.116 safari/537.36 accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8 referer: https://developer.mozilla.org/ accept-encoding: gzip, deflate, sdch, br accept-charset: iso-8859-1,utf-8;q=0.7,*;q=0.7 accept-language: en-us,en;q=0.8,es;q=0.6 cookie: sessionid=6ynxs23n521lu21b1t136rhbv7ezngie; csrftoken=zipujsazv6pcgcbjscj1zu6pqzbfmuat; dwf_section_edit=false; dwf_sg_task_completion=false; _gat=1; _ga=ga1.2.1688886003.1471911953; ffo=true the first and second lines contain most of the information we talked about above: the type of request (get).
...: apache x-backend-server: developer1.webapp.scl3.mozilla.com vary: accept,cookie, accept-encoding content-type: text/html; charset=utf-8 date: wed, 07 sep 2016 00:11:31 gmt keep-alive: timeout=5, max=999 connection: keep-alive x-frame-options: deny allow: get x-cache-info: caching content-length: 41823 <!doctype html> <html lang="en-us" dir="ltr" class="redesign no-js" data-ffo-opensanslight=false data-ffo-opensans=false > <head prefix="og: http://ogp.me/ns#"> <meta charset="utf-8"> <meta http-equiv="x-ua-compatible" content="ie=edge"> <script>(function(d) { d.classname = d.classname.replace(/\bno-js/, ''); })(document.documentelement);</script> ...
...37.36 content-type: application/x-www-form-urlencoded accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8 referer: https://developer.mozilla.org/profiles/hamishwillee/edit accept-encoding: gzip, deflate, br accept-language: en-us,en;q=0.8,es;q=0.6 cookie: sessionid=6ynxs23n521lu21b1t136rhbv7ezngie; _gat=1; csrftoken=zipujsazv6pcgcbjscj1zu6pqzbfmuat; dwf_section_edit=false; dwf_sg_task_completion=false; _ga=ga1.2.1688886003.1471911953; ffo=true csrfmiddlewaretoken=zipujsazv6pcgcbjscj1zu6pqzbfmuat&user-username=hamishwillee&user-fullname=hamish+willee&user-title=&user-organization=&user-location=australia&user-locale=en-us&user-timezone=australia%2fmelbourne&user-irc_nickname=&user-interests=&user-expertise=&user-twitter_url=&user-stackoverflow_url=&user-linkedin_u...

Componentizing our React app - Learn web development
the first (eat) should have a value of true; the rest should be false: <todo name="eat" completed={true} /> <todo name="sleep" completed={false} /> <todo name="repeat" completed={false} /> as before, we must go back to todo.js to actually use these props.
... to follow the same pattern we had initially, let's give each instance of the <todo /> component an id in the format of todo-i, where i gets larger by one every time: <todo name="eat" completed={true} id="todo-0" /> <todo name="sleep" completed={false} id="todo-1" /> <todo name="repeat" completed={false} id="todo-2" /> now go back to todo.js and make use of the id prop.
... in src/index.js, make a new const beneath the final import, but above reactdom.render(): const data = [ { id: "todo-0", name: "eat", completed: true }, { id: "todo-1", name: "sleep", completed: false }, { id: "todo-2", name: "repeat", completed: false } ]; next, we'll pass data to <app /> as a prop, called tasks.

Focus management with Vue refs - Learn web development
focusoneditbutton() { const editbuttonref = this.$refs.editbutton; editbuttonref.focus(); } next, add a call to this.focusoneditbutton() at the end of the itemedited() and editcancelled() methods: itemedited(newitemname) { this.$emit("item-edited", newitemname); this.isediting = false; this.focusoneditbutton(); }, editcancelled() { this.isediting = false; this.focusoneditbutton(); }, try editing and then saving/cancelling a to-do item via your keyboard.
... you might now be thinking "hey, don’t we set isediting=false before we try to access the ref, so therefore shouldn't the v-if now be displaying the button?” this is where the virtual dom comes into play.
... because vue is trying to optimize and batch changes, it won't immediately update the dom when we set isediting to false.

Accessibility API cross-reference
a checkbox; aria has two kinds: use checkbox if you need to express 'mixed' state (some of the descendents are true, some are false), otherwise use switch or (preferred in html) <input type=checkbox>, which are true/false only.
... marquee the main menu bar below the app's title bar menubar menu_bar menu_bar menubar a menu item menuitem menu_item menu_item menuitem a menuitem with a checkable state whose possible values are true, false, or mixed.
... n/a n/a aria-details this is for expandable items that are not expanded, such as folded tree branches or accordions collapsed collapsed collapsed aria-expanded=false different from xul's collapsed="true" attribute which indicates something is hidden this is the default button or menu item default n/a n/a identifies the element that provides an error message for the object.

Adding a new event
if acopytargets is false, don't copy its event target related members.
...therefore, super classes always set it false.
...if your event cannot be fired easy, you should add the test but canrun should return false and call todo().

Listening to events on all tabs
if any registered progress listener returns false from this method then the attempt to refresh will be blocked.
...false if awebprogress is requesting a redirection to a different uri.
...false if the refresh should be aborted.

Cross Process Object Wrappers
for example, this frame script sends a dom node to chrome when the user clicks it, as the clicked property of the third argument: // frame script addeventlistener("click", function (event) { sendasyncmessage("my-e10s-extension-message", {}, { clicked : event.target }); }, false); in the chrome script, the dom node is now accessible through a cross process object wrapper, as a property of the objects property of the message.
...*/ var button = content.document.getelementbyid("click-me"); button.addeventlistener("mouseover", function (event) { sendasyncmessage("my-addon-message", {}, { element : event.target }); }, false); // chrome script /* load the frame script, then listen for the message.
...*/ browsermm.loadframescript("chrome://my-addon/content/frame-script.js", false); browsermm.addmessagelistener("my-addon-message", function(message) { let wrapper = message.objects.element; wrapper.addeventlistener("click", function() { console.log("they clicked"); }); }); mapping content documents to xul browsers a common pattern is to get the xul <browser> that corresponds to a content document.

mozbrowsersecuritychange
extendedvalidation a boolean indicating if the current ssl certificate is an extended validation certificate (true) or not (false).
... trackingcontent a boolean indicating if tracking content is present on the current page (true) or not (false).
... mixedcontent a boolean indicating if mixed content is present on the current page (true) or not (false).

HTMLIFrameElement.setVisible()
on the contrary, if its visible state is set to false, it has low priority over the resources it needs.
...however, if the visible state is set to false, window.requestanimationframe will be called only when there are free resources to do it.
... parameters visible a boolean that indicates if the browser <iframe> visible state is true or false.

Addon
foreigninstall read only boolean true or false depending on whether the add-on is a third party add-on installation or not.
... iscompatible read only boolean true or false depending on whether the add-on is compatible with the current application version and platform version.
... isplatformcompatible read only boolean true or false depending on whether the add-on is compatible with the current operating system.

InstallListener
a listener may return false to cancel the download.
...a listener may return false to cancel the download.
...a listener may return false to cancel the install.

FileUtils.jsm
followlinks optional true if links should be followed, false otherwise.
... shouldcreate optional true if the directory hierarchy specified in patharray should be created if it does not exist, false otherwise.
... followlinks optional true if links should be followed, false otherwise location specified.

OS.File.Error
becauseexists true if the operation failed because a file or directory exists, false otherwise.
... becausenosuchfile true if the operation failed because a file or directory does not exist, false otherwise.
... becauseclosed true if the operation failed because a file or directory is closed, false otherwise.

OS.File.Info
instances of os.file.info cross-platform attributes isdir true if the file is a directory, false otherwise.
... issymlink true if the false is a symbolic link, false otherwise.
... (as of firefox 38 this is always true on all systems, this is a bug: bugzilla 1145885) (on windows this returns false for hard links) size the number of bytes in the file.

PromiseWorker.jsm
complete example following example provides resolvetest function, which resolves the promise when true is passed as an argument, and rejects the promise when false is passed as an argument, and post messages to it from the main thread.
...nctrue = myworker.post('resolvetest', [true]); promise_domyfunctrue.then( function(aval) { console.log('fullfilled - promise_domyfunctrue - ', aval); }, function(areason) { console.error('rejected - promise_domyfunctrue - ', areason); } ).catch( function(acaught) { console.error('caught - promise_domyfunctrue - ', acaught); } ); var promise_domyfuncfalse = myworker.post('resolvetest', [false]); promise_domyfuncfalse.then( function(aval) { console.log('fullfilled - promise_domyfuncfalse - ', aval); }, function(areason) { console.error('rejected - promise_domyfuncfalse - ', areason); } ).catch( function(acaught) { console.error('caught - promise_domyfuncfalse - ', acaught); } ); result running the ...
...code above will log the following information to the console: "fullfilled - promise_domyfunctrue - " "you sent to promiseworker argument of: `true`" bootstrap.js line 8 "rejected - promise_domyfuncfalse - " "you passed in a non-true value for shouldresolve argument and therefore this will reject the main thread promise" bootstrap.js line 25 other examples github :: promiseworker with backward compatability - this example is of a firefox addon that copies and pastes in the contents of promiseworker.js and promiseworker.jsm so that it works all the way back till the firefox version in which the promise interface was frozen.

Sqlite.jsm
here is an example: components.utils.import("resource://gre/modules/sqlite.jsm"); try { const conn = await sqlite.openconnection({ path: "mydatabase.sqlite", sharedmemorycache: false }); // connection is the opened sqlite connection (see below for api).
... it is possible to automatically close the connection when the browser is closed with the shutdown hook: const conn = await sqlite.openconnection({ path: "mydatabase.sqlite", sharedmemorycache: false }); try { sqlite.shutdown.addblocker("my connection closing", async () => await conn.close()); } catch (e) { // it's too late to block shutdown, just close the connection.
... these functions receive the following arguments: readonly (optional) if true the clone will be read-only, default is false.

PR_ASSERT
terminates execution when a given expression is false.
... syntax #include <prlog.h> void pr_assert ( expression ); parameters the macro has this parameter: expression any valid c language expression that evaluates to true or false.
...when the result is zero (false) the application terminates; otherwise the application continues.

PR_STATIC_ASSERT
prevents code from compiling when an expression has the value false at compile time.
... syntax #include <prlog.h> pr_static_assert ( expression ); parameters the macro has this parameter: expression any valid expression which evaluates at compile-time to true or false.
...when the result is zero (false) program compilation will fail with a compiler error; otherwise compilation completes successfully.

NSS Sample Code sample5
ectpublickeyinfo; char *pvtkstr = base64_encoded_privatekeyinfo; secitem der; secitem nickname; pk11slotinfo *slot = null; /* initialize nss * you need to explicitly authenticate to the internal token if you use * nss_init insteadf of nss_nodb_init * invoke this after getting the internal token handle * pk11_authenticate(slot, pr_false, null); */ rv = nss_nodb_init("."); if (rv != secsuccess) { fprintf(stderr, "nss initialization failed (err %d)\n", pr_geterror()); goto cleanup; } /* get internal slot */ slot = pk11_getinternalkeyslot(); if (slot == null) { fprintf(stderr, "couldn't find slot (err %d)\n", pr_geterror()); goto cleanup; } rv = atob_convertasciitoitem(&der, pubk...
...str); if (rv!= secsuccess) { fprintf(stderr, "atob_convertasciitoitem failed %d\n", pr_geterror()); goto cleanup; } spki = seckey_decodedersubjectpublickeyinfo(&der); secitem_freeitem(&der, pr_false); pubkey = seckey_extractpublickey(spki); if (pubkey == null) { fprintf(stderr, "couldn't extract public key (err %d)\n", pr_geterror()); goto cleanup; } modulus_len = seckey_publickeystrength(pubkey); fprintf(stderr, "public key modulus %d bytes\n", modulus_len); buf1 = (char *)malloc(modulus_len); buf2 = (char *)malloc(modulus_len); /* initialize buf1 */ for (i=0;i<modulus_len;i++) { buf1[i]= (i %26) + 'a'; } buf1[modulus_len-1] = '\0'; fprintf(stderr, "buffer being encrypted = \n%s\n", buf1); /* encrypt buf1, result will be in buf2 *...
... * publicvalue arg (4th) can be null for rsa key - i think it is even * ignored */ pk11_importderprivatekeyinfoandreturnkey(slot, &der, null, null, pr_false, pr_true, ku_all, &pvtkey, null); secitem_freeitem(&der, pr_false); if (pvtkey == null) { fprintf(stderr, "couldn't extract private key (err %d)\n", pr_geterror()); goto cleanup; } /* clear buf1 */ for (i=0;i<modulus_len;i++) { buf1[i]= '\0'; } /* decrypt buf2, result will be in buf1 */ rv = pk11_pubdecryptraw(pvtkey, b...

NSS PKCS11 Functions
if the slot is implemented in software, pr_false.
...if token is disabled or missing, pr_false.
...otherwise, pr_false.

pkfnc.html
if the slot is implemented in software, pr_false.
... if token is disabled or missing, pr_false.
... otherwise, pr_false.

Hacking Tips
│ auto funcptr = js_data_to_func_ptr(exportfuncptr, codebase() + func.entryoffset()); │ if (!call_generated_2(funcptr, exportargs.begin(), &tlsdata_)) │ return false; after it's set, x/64i funcptr will show you the trampoline code.
... for (; iter != current->end(); iter++) { ionspew(ionspew_codegen, "instruction %s", iter->opname()); […] masm.store16(imm32(iter->id()), address(stackpointer, -8)); // added if (!iter->accept(this)) return false; […] } this modification will add an instruction which abuse the stack pointer to store an immediate value (the lir id) to a location which would never be generated by any sane compiler.
...the other being disable this check in "about:config", by temporarily switching "security.fileuri.strict_origin_policy" to false note 2: the files can be very big and take a long time to load in the browser.

JS::Value
the data in a js::value can be accessed using these member functions: js type js::value type tests constructor accessors mutators null val.isnull() js::nullvalue() n/a val.setnull() undefined val.isundefined() js::undefinedvalue() n/a val.setundefined() boolean val.isboolean(), val.istrue(), val.isfalse() js::booleanvalue(bool), js::truevalue(), js::falsevalue() val.toboolean() val.setboolean(bool) number val.isint32(), val.isdouble(), val.isnumber() js::numbervalue(any number type), js::int32value(int32_t), js::doublevalue(double), js::float32value(float) val.toint32(), val.todouble(), val.tonumber() val.setint32(int32_t), val.setnumber(uint32_t), val.setnumber(dou...
...the number mutators attempt to use int32_t representation for compatible input values, returning true when int32 could be used and false when double representation was required.
... js type jsval type tests jsval constants and constructors jsval accessors null jsval_is_null(v) jsval_null undefined jsval_is_void(v) jsval_void boolean jsval_is_boolean(v) jsval_true, jsval_false, boolean_to_jsval(b) jsval_to_boolean(v) number jsval_is_number(v), jsval_is_int(v), jsval_is_double(v) jsval_zero, jsval_one, int_to_jsval(i), double_to_jsval(d) jsval_to_int(v), jsval_to_double(v) string jsval_is_string(v) string_to_jsval(str) jsval_to_string(v), js_getstringchars(str), js_getstringlength(str) object !jsval_is_primitive(v) o...

JSAutoByteString
examples use constructor arguments { jsstring *str = js::tostring(cx, strval); if (!str) return false; jsautobytestring bytes(cx, str); /* calls js_encodestring internally */ if (!bytes) return false; /* ...do something with bytes...
...*/ } use method to encode string { js::rootedstring str(cx, js::tostring(cx, strval)); if (!str) return false; jsautobytestring bytes; if (!bytes.encodeutf8(cx, str)) /* calls js_encodestringtoutf8 internally */ return false; /* ...do something with bytes...
...*/ } take ownership of other buffer { char *buff = cx->pod_malloc<char>(length + 1); if (!buff) return false; memcpy(buff, other_buff, length + 1) jsautobytestring bytes; bytes.initbytes(buff); /* ...do something with bytes...

JSVAL_TO_BOOLEAN
that is, v must be either jsval_true or jsval_false.
...the result is js_true or js_false respectively.
...js_false is 0; js_true is 1.

JS_AlreadyHasOwnProperty
*foundp receives true if the property is found or false if it is not found.
...if the property is not found on obj, this sets *foundp to false and returns true (to indicate that no error occurred).
... if the search fails with an error or exception, this returns false.

JS_DeleteElement2
on success, *succeeded receives false if the property was not deleted because it is permanent and true otherwise.
...otherwise it returns false and the value of *succeeded is undefined.
... for javascript 1.2 and earlier, if deletion fails because the property is permanent, js_deleteelement2 reports the error and returns false.

JS_EncodeCharacters
*/ size_t dstlen = 0; if (!js_encodecharacters(cx, src, srclen, null, &dstlen)) return js_false; /* allocate.
... */ char *dst = (char *) js_malloc(cx, dstlen); if (dst == null) return js_false; /* convert characters to bytes.
...otherwise it reports an error and returns js_false.

JS_GetPropertyAttributes
if no error occurs, *foundp receives js_true if the specified property is found and js_false if it is not found.
... if an error occurs, the return value is js_false, and the values left in *attrsp and *foundp are unspecified.
... if obj does not have the specified property, or if it inherits it from some other object (on its prototype chain, for example), then *foundp is set to js_false.

JS_HasElement
on success, it stores true to *foundp, false otherwise.
...if not, it sets *foundp to false and returns true (to indicate no error occurred).
... if the search fails with an error or exception, js_haselement returns false, and the value left in *foundp is undefined.

JS_HasOwnProperty
on success, js_hasownproperty stores true in this variable if obj has an own property with the given name, and false if not.
... if the object obj has no such property, the function sets *foundp to false and returns true (to indicate that no error occurred).
... if an error occurs during the search, the function returns false, and the value of *foundp is undefined.

JS_HasProperty
on success, js_hasproperty stores true in this variable if obj has a property with the given name, and false if not.
...if the object obj has no such property, the function sets *foundp to false and returns true (to indicate that no error occurred).
... if an error occurs during the search, the function returns false, and the value of *foundp is undefined.

JS_ResolveStandardClass
false otherwise.
...if id does not name a standard class or a top-level property induced by initializing a standard class, store false in *resolved and just return true.
... return false on error, as usual for bool result-typed api entry points.

JS_SetPropertyAttributes
if js_setpropertyattributes cannot locate an object with the specified property, it returns js_false, and the value left in *foundp is undefined.
... if the specified property or the specified object does not exist, foundp is set to js_false.
...if not, it returns js_false.

XPCOM array guide
can or should be modified, then use nsimutablearray: // array is read-only because it uses nsiarray void printsize(nsiarray* elements) { pruint32 count; elements->getlength(&count); printf("there are %d elements.\n", count); } // using nsimutablearray, so callee may modify void tweakarray(nsimutablearray* elements) { elements->removeelementat(0); elements->appendelement(newelement, pr_false); } while it is usually possible to call queryinterface on an nsiarray to get access to the nsimutablearray interface, this is against convention and it should be avoided.
... *elements->removeelementat(0); *elements->appendelement(newelement, pr_false); } in-place enumeration when accessing all members of an nsiarray, in-place enumeration is preferred over indexed access.
...for instance: pr_callback prbool getfirstvisible(nsielement* element, void* closure) { prbool isvisible; element->isvisible(&isvisible); // stop at first object if (isvisible) { ns_static_cast(closureobject*,closure)->element = element; return pr_false; } return pr_true; } ...

Finishing the Component
if these two strings do not match, then the component returns return false and blocks the load.
... *_retval = pr_false; nsresult rv; nscomptr<nsiservicemanager> servman; rv = ns_getservicemanager(getter_addrefs(servman)); if (ns_failed(rv)) return rv; nscomptr<nsiioservice> mioservice; // get a pointer to the ioservice rv = servman->getservicebycontractid("@mozilla.org/network/io-service;1", ns_get_iid(nsiioservice), ...
... getter_addrefs(mioservice)); if (ns_failed(rv)) return rv; urlnode* node = mrooturlnode; prbool match = pr_false; while (node) { nscomptr<nsiuri> uri; nsembedcstring urlstring(node->urlstring); rv = mioservice->newuri(urlstring, nsnull, nsnull, getter_addrefs(uri)); // if anything bad happens, just abort if (ns_failed(rv)) return rv; nsembedcstring host; uri->gethost(host); if (strcmp(hosttoload.get(), host.get()) == 0) { // match found.

Mozilla internal string guide
ause mozilla strings are always a single buffer, iteration over the characters in the string is done using raw pointers: /** * find whether there is a tab character in `data` */ bool hastab(const nsastring& data) { const char16_t* cur = data.beginreading(); const char16_t* end = data.endreading(); for (; cur < end; ++cur) { if (char16_t('\t') == *cur) return true; } return false; } note that `end` points to the character after the end of the string buffer.
...the return value is pr_true or pr_false, indicating whether or not the string was found.
... these versions return 'false' instead of aborting if allocation fails .

Components.isSuccessCode
summary determines whether a given xpcom return code (that is, an nsresult value) indicates the success or failure of an operation, returning true or false respectively.
... const cc = components.classes; const ci = components.interfaces; const cr = components.results; // global flags polled externally var copyfailed = false; var copyinprogress = false; function copybufferedstream(instream, outstream) { var copyobserver = { onstartrequest: function(request, context) { copyinprogress = true; }, onstoprequest: function(request, context, statuscode) { copyinprogress = false; // did the copy fail?
...rue; }, queryinterface: function(aiid) { if (aiid.equals(ci.nsirequestobserver) || aiid.equals(ci.nsisupports)) return this; throw cr.ns_error_no_interface; } }; var copier = cc["@mozilla.org/network/async-stream-copier;1"] .createinstance(ci.nsiasyncstreamcopier); copier.init(instream, outstream, null, true, false, 8192, true, true); copier.asynccopy(copyobserver, null); } ...

Components.utils.Sandbox
if the sandbox interacts with untrusted content this should be set to false when possible to further reduce possible attack surface.
...default: false.
... var sandboxscript = 'alert($)'; var options = { sandboxprototype: content, wantxrays: false // only set this to false if you need direct access to the page's javascript.

IAccessibleTableCell
return value s_false if there is no header, [out] values are null and 0 respectively.
...[propget] hresult isselected( [out] boolean isselected ); parameters isselected returns true if the specified cell is selected and false otherwise.
... return value s_false if there is no header, [out] values are null and 0 respectively.

inIDOMUtils
in particular, this will be false if certain css white-space styles are in effect.
... return value true if the property is inherited, otherwise false.
... return value true if lock exists, false otherwise clearpseudoclasslocks() removes any pseudo-class locks from the element.

mozIStorageVacuumParticipant
return value return true to allow the vacuum operation to proceed, or false if you don't want the database to be vacuumed.
... you may wish to return false, for example, if you're in the middle of an operation that you don't want to (or can't) interrupt.
...void onendvacuum( in boolean asucceeded ); parameters asucceeded true if the vacuum operation was successful, or false if it wasn't successful.

nsIApplicationCacheChannel
the default value is false.
... loadedfromapplicationcache prbool true if the resource was loaded from the application cache, otherwise false.
... this value may be false even if the resource is assigned to an application cache if, for example, it was loaded as a fallback.

nsIAuthPrompt
return value true for ok, false for cancel.
... return value true for ok, false for cancel.
... return value true for ok, false for cancel.

nsICacheSession
if false, expired entries will be returned (useful for offline mode and clients, such as http, that can update the valid lifetime of cached content).
...if blockingmode is set to false, it will return ns_error_cache_wait_for_validation rather than block when another descriptor has been given write access but hasn't validated the entry yet.
...blockingmode true or false value to turn blocking mode for calling the thread to on/off respectively.

nsIClipboard
otherwise it returns false.
...otherwise it returns false.
...otherwise it returns false.

nsIDocShell
note: starting in gecko 8.0, isactive is false for documents in minimized windows.
... top should be true for the toplevel docshell that is being restored; it will be set to false when this method is called for child docshells.
...return value returns true if the docshell is being destroyed, false otherwise.

nsILocalFileMac
if followlinks is false, returns the unresolved alias file.
...if followlinks is false, returns the unresolved alias file.
...if followlinks is false, returns the unresolved alias file.

nsILoginManager
return value true if the form was successfully filled out; otherwise false.
... return value true if login saving is enabled for the host, otherwise false.
...if false, login saving is disabled.

nsIMemory
if false, the flush will be scheduled to happen when the app is idle.
...otherwise false.
... note: from gecko 2.0 always returns false.

nsIMenuBoxObject
openedwithkey boolean true if the menubar was opened using the keyboard; otherwise false.
... return value true if the event was handled, false if not.
... openmenu() void openmenu( in boolean openflag ); parameters openflag true to open the menu or false to close it.

nsIMsgDBHdr
if false mark as undread.
...if false remove flag.
...if false mark as not having attachments.

nsINavHistoryService
return value returns true if this uri would be added to the history, otherwise returns false.
...this will be "0" if the uri is not valid for adding to history (canadduri = false).
...if ownsweak is false, the history service will keep an owning reference to the observer.

nsIParentalControlsService
aflag pass true if the event was blocked or false if it was allowed.
... return value true if the block was successfully overridden, otherwise false.
... return value true if the block was successfully overridden, otherwise false.

nsIPlacesImportExportService
loads the given bookmarks.html file and replaces it with the current bookmarks hierarchy (if aisinitialimport is true) or appends it (if aisinitialimport is false).
...observers will be passed through their data parameters either "html" if aisinitialimport is false or "html-initial" if aisinitialimport is true.
...observers will be passed through their data parameters either "html" if aisinitialimport is false or "html-initial" if aisinitialimport is true.

nsISelection
if partlycontained is set to pr_false, the function only returns true when the entire node is part of the selection.
... boolean containsnode( in nsidomnode node, in boolean partlycontained ); parameters node the nsidomnode to look for partlycontained if partlycontained is set to pr_false, the function only returns true when the entire node is part of the selection.
...void selectionlanguagechange( in boolean langrtl ); parameters langrtl is pr_true if the new language is right-to-left or pr_false if the new language is left-to-right.

nsISessionStore
will always be false when in private browsing mode.
... if the preference browser.sessionstate.enabled is false when this method is called, then you will get an exception about "awindows[i] has no properties".
...if it's false, the tabs in astate are added to the tabs already in the window.

nsITaskbarPreviewButton
this is false by default.
...if false, the button doesn't participate in the layout of buttons underneath the preview.
... this is false by default.

nsITaskbarPreviewController
return value true if you want a frame drawn around the preview, otherwise false.
... return value true if you want a frame drawn around the thumbnail, otherwise false.
... return value true if the top level window corresponding to the preview should be activated, false if activation is not accepted.

nsIThread
since other threads may add events to the current thread, it's possible that by the time this method returns, the event queue may no longer be empty, even if a false result is reported.
...if false, this method returns immediately if the queue is empty.
... return value returns true if an event was processed, or false if there were no pending events.

nsIURI
return value true if the two uris represent the same location; otherwise false.
... return value true if the two uris represent the same location; otherwise false.
... return value true if the uri is for the specified scheme; otherwise false.

nsIXPCScriptable
implementations may skip writing to *_retval unless they want to return pr_false.
... return value this should (although does not need to) return pr_true to indicate success or must return pr_false to indicate failure.
... return value this should (although does not need to) return pr_true to indicate success or must return pr_false to indicate failure.

Mail and RDF
gaccounts:/ +-- http://home.netscape.com/nc-rdf#child --> | imap://alecf@imap.mywork.com | +-- http://home.netscape.com/nc-rdf#isserver --> "true" | +-- http://home.netscape.com/nc-rdf#child --> | imap://alecf@imap.mywork.com/inbox | +-- http://home.netscape.com/nc-rdf#totalmessages --> "4" | +-- http://home.netscape.com/nc-rdf#isserver --> "false" | +-- http://home.netscape.com/nc-rdf#messagechild --> | | imap_message://alecf@imap.mywork.com/inbox#1 | +-- http://home.netscape.com/nc-rdf#messagechild --> | | imap_message://alecf@imap.mywork.com/inbox#2 | +-- http://home.netscape.com/nc-rdf#messagechild --> | | imap_message://alecf@imap.mywork.com/inbox#3 | +-...
... +-- http://home.netscape.com/nc-rdf#child --> | mailbox://alecf@pop.mywork.com | +-- http://home.netscape.com/nc-rdf#isserver --> "true" | +-- http://home.netscape.com/nc-rdf#child --> | mailbox://alecf@pop.mywork.com/inbox | +-- http://home.netscape.com/nc-rdf#totalmessages --> "2" | +-- http://home.netscape.com/nc-rdf#isserver --> "false" | +-- http://home.netscape.com/nc-rdf#messagechild --> | | mailbox_message://alecf@pop.mywork.com/inbox#1 | +-- http://home.netscape.com/nc-rdf#messagechild --> | mailbox_message://alecf@pop.mywork.com/inbox#2 | etc...
... an example of how this might work inside the datasource: var msgcountarc = rdf.getresource("http://home.netscape.com/nc-rdf#totalmessages"); function gettarget(target, property, unused) { var folder = target.queryinterface(components.interfaces.nsimsgfolder); if (property == msgcountarc) { var msgcount = folder.gettotalmessages(false); var result = rdf.getliteral(msgcount.tostring()); return result; } } asynchronously notifying rdf when a mail object's data changes and the data is reflected in rdf by notifying all of the observers that rdf has registered with the datasource.

Adding items to the Folder Pane
the following code snippet listens for that event: let gnumbersext = { load: function gne_load() { window.removeeventlistener("load", gnumbersext.load, false); let tree = document.getelementbyid("foldertree"); tree.addeventlistener("maprebuild", gnumbersext._insert, false); }, _insert: function gne__insert() { // this function is called when a rebuild occurs } }; window.addeventlistener("load", gnumbersext.load, true); the structure of folder-tree-items the folder pane stores its current display data in a property called _rowmap.
...first, our "numbers" container looks like this: let containerrow = { _numbers: 3, id: "numbers-main-container", text: "numbers", level: 0, open: false, _children: null, get children() { if (!this._children) { this._children = []; for (var i = 1; i <= this._numbers; i++) this._children.push(new numberrow(i)); } return this._children; }, getproperties: function gne_getprops() { // put your css attributes here }, command: function gne_command() { ...
...tservice) .alert(window, null, this.text); } }; second, our child items (the numbers 1, 2, and 3) are copies of the following prototype: function numberrow(anumber) { this._number = anumber; } numberrow.prototype = { get id() { return "numbers-child-row-" + this._number; }, get text() { return this._number; }, level: 1, open: false, children: [], getproperties: function gne_kid_getprops() {}, // no-op command: function gne_kid_command() { // just going to alert, to do something here components.classes["@mozilla.org/embedcomp/prompt-service;1"] .getservice(components.interfaces.nsipromptservice) .alert(window, null, this.text); } }; putting it a...

Type conversion
10)() is converted to ctypes.char.ptr type implicit conversion can be tested in the following way: var mystruct = ctypes.structtype("mystructtype", [ { "v": ctypes.bool } ])(); mystruct.v = 1; console.log(mystruct.v.tostring()); // 'true' boolean type target type source converted value ctypes.bool js boolean src js number (0 or 1) if src == 0: false if src == 1: true var mystruct = ctypes.structtype("mystructtype", [ { "v": ctypes.bool } ])(); mystruct.v = true; console.log(mystruct.v.tostring()); // 'true' mystruct.v = false; console.log(mystruct.v.tostring()); // 'false' mystruct.v = 1; console.log(mystruct.v.tostring()); // 'true' mystruct.v = 0; console.log(mystruct.v.tostring()); // 'false' mystruct.v = 10; // thr...
...ows error mystruct.v = "a"; // throws error integer types target type source converted value ctypes.char16_t js string (only if its length == 1) src.charcodeat(0) any integer types js number (only if fits to the size) src js boolean if src == true: 1 if src == false: 0 var mystruct = ctypes.structtype("mystructtype", [ { "v": ctypes.char16_t } ])(); mystruct.v = 0x41; console.log(mystruct.v.tostring()); // "a" mystruct.v = true; console.log(mystruct.v.tostring()); // "\x01" mystruct.v = "x"; console.log(mystruct.v.tostring()); // "x" mystruct.v = "xx"; // throws error var mystruct = ctypes.structtype("mystructtype", [ { "v": ctypes.int16_t } ])(); mystruct.v = 0x41; console.log(mystru...
..."123"); // string "123" is parsed as 10-base string explicit convert tries implicit convert first, and if it fails, the following rules are applied: boolean type target type source converted value ctype.bool js value toboolean(src) console.log(ctypes.bool("123").tostring()); // 'ctypes.bool(true)' console.log(ctypes.bool("").tostring()); // 'ctypes.bool(false)' integer types target type source converted value any integer types js number except -infinity, infinity, nan c-style cast -infinity 0 infinity nan ctypes.int64 c-style cast ctypes.uint64 js string with base-10 or base-16 string (only if fits to the size) parse src as base-10 or base-16 string ...

URLs - Plugins
to post data from a memory buffer, set the flag file to false, the buffer buf to the data to post, and len to the length of the buffer.
... char* ppostdata = "content-type:\tapplication/x-www-form-urlencoded\ncontent-length:\t17\n\nname=aaashun@gmail.com\n"; uint32 npostdatalen = (uint32)strlen(ppostdata); npn_posturl(npinstance, "http://www.baidu.com","_blank", npostdatalen, ppostdata, false); uploading files to an ftp server plug-ins can use npn_posturl or npn_posturlnotify to upload files to a remote server using ftp.
... char* mydata = "\nhi fred, this is a message from my plug-in!"; uint32 mylength = strlen(mydata) + 1; err = npn_posturlnotify(instance, "mailto:fred@example.com", null, mylength, mydata, false); the example starts by defining the mail message, mydata, and its length, mylength.

Waterfall - Firefox Developer Tools
ode like this: var iterations = 70; var multiplier = 1000000000; function calculateprimes() { console.time("calculating..."); var primes = []; for (var i = 0; i < iterations; i++) { var candidate = i * (multiplier * math.random()); var isprime = true; for (var c = 2; c <= math.sqrt(candidate); ++c) { if (candidate % c === 0) { // not prime isprime = false; break; } } if (isprime) { primes.push(candidate); } } console.timeend("calculating..."); return primes; } the waterfall's output will look something like this: the marker is labeled with the argument you passed to console.time(), and when you select the marker, you can see the program stack in the right-hand sidebar.
... for example, consider code like this: var timerbutton = document.getelementbyid("timer"); timerbutton.addeventlistener("click", handleclick, false); function handleclick() { console.time("timer"); runtimer(1000).then(timerfinished); } function timerfinished() { console.timeend("timer"); console.log("ready!"); } function runtimer(t) { return new promise(function(resolve) { settimeout(resolve, t); }); } the waterfall will display a marker for the period between time() and timeend(), and if you select it, you'll see the asy...
...nction calculateprimes() { console.time("calculating..."); var primes = []; for (var i = 0; i < iterations; i++) { if (i % 10 == 0) { console.timestamp(i.tostring()); } var candidate = i * (multiplier * math.random()); var isprime = true; for (var c = 2; c <= math.sqrt(candidate); ++c) { if (candidate % c === 0) { // not prime isprime = false; break; } } if (isprime) { primes.push(candidate); } } console.timeend("calculating..."); return primes; } in the waterfall you'll now see something like this: ...

Attr - Web APIs
originally, it returned true if the attribute was explicitly specified in the source code or by a script, and false if its value came from the default one defined in the document's dtd.
... hasattributes() obsolete since gecko 21.0 this method now always returns false.
... haschildnodes() this method now always returns false.

AudioTrack.enabled - Web APIs
if the track is disabled by setting enabled to false, the track is muted and does not produce audio.
... syntax isaudioenabled = audiotrack.enabled; audiotrack.enabled = true | false; value the enabled property is a boolean whose value is true if the track is enabled; enabled tracks produce audio while the media is playing.
... setting enabled to false effectively mutes the audio track, preventing it from contributing to the media's audio performance.

CSS.registerProperty() - Web APIs
inherits a boolean value defining whether the defined property should be inherited (true), or not (false).
... defaults to false.
... examples the following will register a custom property, --my-color, using registerproperty(), as a color, give it a default value, and have it not inherit its value: window.css.registerproperty({ name: '--my-color', syntax: '<color>', inherits: false, initialvalue: '#c0ffee', }); in this example, the custom property --my-color has been registered using the syntax <color> .

Using the CSS properties and values API - Web APIs
css.registerproperty the following will register a css custom properties, --my-prop, using css.registerproperty, as a color, give it a default value, and have it not inherit its value: window.css.registerproperty({ name: '--my-prop', syntax: '<color>', inherits: false, initialvalue: '#c0ffee', }); @property the same registration can take place in css.
... the following will register a css custom properties, --my-prop, using @property, as a color, give it a default value, and have it not inherit its value: @property --my-prop { syntax: '<color>'; inherits: false; initial-value: #c0ffee; } using registered custom properties one of the advantages of registering a property is that the browser now knows how it should handle your custom property through things like transitions!
...istered { --unregistered: #c0ffee; background-image: linear-gradient(to right, #fff, var(--unregistered)); transition: --unregistered 1s ease-in-out; } .unregistered:hover, .unregistered:focus { --unregistered: #b4d455; } button { height: 40vh; display: block; width: 100%; font-size: 3vw; } window.css.registerproperty({ name: '--registered', syntax: '<color>', inherits: false, initialvalue: 'red', }); while not functionally accurate, a good way to think about the difference between the unregistered property in the above example and the registered property is the difference between a <custom-ident> and a number when trying to animate height.

Cache.keys() - Web APIs
it defaults to false.
... ignoremethod: a boolean that, when set to true, prevents matching operations from validating the request http method (normally only get and head are allowed.) it defaults to false.
...it defaults to false.

Cache.matchAll() - Web APIs
it defaults to false.
... ignoremethod: a boolean that, when set to true, prevents matching operations from validating the request http method (normally only get and head are allowed.) it defaults to false.
...it defaults to false.

CacheStorage.match() - Web APIs
it defaults to false.
... ignoremethod: a boolean that, when set to true, prevents matching operations from validating the request http method (normally only get and head are allowed.) it defaults to false.
...it defaults to false.

CanvasRenderingContext2D.imageSmoothingEnabled - Web APIs
the imagesmoothingenabled property of the canvasrenderingcontext2d interface, part of the canvas api, determines whether scaled images are smoothed (true, default) or not (false).
...set this property to false to retain the pixels' sharpness.
...new image(); img.src = 'https://interactive-examples.mdn.mozilla.net/media/examples/star.png'; img.onload = function() { const w = img.width, h = img.height; ctx.filltext('source', w * .5, 20); ctx.drawimage(img, 0, 24, w, h); ctx.filltext('smoothing = true', w * 2.5, 20); ctx.imagesmoothingenabled = true; ctx.drawimage(img, w, 24, w * 3, h * 3); ctx.filltext('smoothing = false', w * 5.5, 20); ctx.imagesmoothingenabled = false; ctx.drawimage(img, w * 4, 24, w * 3, h * 3); }; result specifications specification status comment html living standardthe definition of 'canvasrenderingcontext2d.imagesmoothingenabled' in that specification.

console.assert() - Web APIs
the console.assert() method writes an error message to the console if the assertion is false.
...if the assertion is false, the message is written to the console.
... console.log('the word is %s', 'foo'); // output: the word is foo ...the use of such a string does not currently work as intended as a parameter for console.assert in all browsers: console.assert(false, 'the word is %s', 'foo'); // correct output in node.js and some browsers // (e.g.

Constraint validation API - Web APIs
willvalidate a read-only boolean property that returns true if the element is a candidate for constraint validation; and false otherwise.
...if the value is invalid, it fires an invalid event at the element and returns false; otherwise it returns true.
... reportvalidity() htmlformelement method checks the element's value against its constraints and also reports the validity status; if the value is invalid, it fires an invalid event at the element, returns false, and then reports the validity status to the user in whatever way the user agent has available.

ConvolverNode.normalize - Web APIs
if normalize is set to false, then the convolution will be rendered with no pre-processing/scaling of the impulse response.
... syntax var audioctx = new audiocontext(); var convolver = audioctx.createconvolver(); convolver.normalize = false; value a boolean.
... convolver.normalize = false; // must be set before the buffer, to take effect convolver.buffer = concerthallbuffer; specifications specification status comment web audio apithe definition of 'normalize' in that specification.

DOMTokenList.replace() - Web APIs
if the first token doesn't exist, replace() returns false immediately, without adding the new token to the token list.
... return value a boolean value, which is true if oldtoken was successfully replaced, or false if not.
...to use with earlier versions of ie, refer to the polyfill at element.classlist#polyfill domtokenlist.prototype.replace = function (a, b) { if (this.contains(a)) { this.add(b); this.remove(a); return true; } return false; } specifications specification status comment domthe definition of 'replace()' in that specification.

Document: drag event - Web APIs
div> <div class="dropzone"></div> <div class="dropzone"></div> css #draggable { width: 200px; height: 20px; text-align: center; background: white; } .dropzone { width: 200px; height: 20px; background: blueviolet; margin-bottom: 10px; padding: 10px; } javascript var dragged; /* events fired on the draggable target */ document.addeventlistener("drag", function(event) { }, false); document.addeventlistener("dragstart", function(event) { // store a ref.
... on the dragged elem dragged = event.target; // make it half transparent event.target.style.opacity = .5; }, false); document.addeventlistener("dragend", function(event) { // reset the transparency event.target.style.opacity = ""; }, false); /* events fired on the drop targets */ document.addeventlistener("dragover", function(event) { // prevent default to allow drop event.preventdefault(); }, false); document.addeventlistener("dragenter", function(event) { // highlight potential drop target when the draggable element enters it if (event.target.classname == "dropzone") { event.target.style.background = "purple"; } }, false); document.addeventlistener("dragleave", function(event) { // reset background of potential drop target when the draggable element leaves it ...
...if (event.target.classname == "dropzone") { event.target.style.background = ""; } }, false); document.addeventlistener("drop", function(event) { // prevent default action (open as link for some elements) event.preventdefault(); // move dragged elem to the selected drop target if (event.target.classname == "dropzone") { event.target.style.background = ""; dragged.parentnode.removechild( dragged ); event.target.appendchild( dragged ); } }, false); specifications specification status comment html living standardthe definition of 'drag event' in that specification.

Document.queryCommandEnabled() - Web APIs
return value returns a boolean which is true if the command is enabled and false if the command isn't.
... the 'paste' command return false not only if the feature is unavailable, but also if the script calling it has insufficient privileges to perform the action.
... example var flg = document.querycommandenabled("selectall"); if(flg) { document.execcommand("selectall", false, null); // command is enabled, run it } specifications specification status comment execcommand ...

How whitespace is handled by HTML, CSS, and in the DOM - Web APIs
as another example, if you have a certain subset of elements that you want to do something to based on whether they are empty (have no child nodes) or not, you could check whether each element is empty using something like node.haschildnodes(), but again, if any target elements contain text nodes, you could end up with false results.
... * * @param nod a node implementing the |characterdata| interface (i.e., * a |text|, |comment|, or |cdatasection| node * @return true if all of the text content of |nod| is whitespace, * otherwise false.
... * @return true if the node is: * 1) a |text| node that is all whitespace * 2) a |comment| node * and otherwise false.

Element: mousedown event - Web APIs
the mouseup event draws the final line segment, sets x and y to 0, and stops further drawing by setting isdrawing to false.
... html <h1>drawing with mouse events</h1> <canvas id="mypics" width="560" height="360"></canvas> css canvas { border: 1px solid black; width: 560px; height: 360px; } javascript // when true, moving the mouse draws on the canvas let isdrawing = false; let x = 0; let y = 0; const mypics = document.getelementbyid('mypics'); const context = mypics.getcontext('2d'); // event.offsetx, event.offsety gives the (x,y) offset from the edge of the canvas.
...wn', e => { x = e.offsetx; y = e.offsety; isdrawing = true; }); mypics.addeventlistener('mousemove', e => { if (isdrawing === true) { drawline(context, x, y, e.offsetx, e.offsety); x = e.offsetx; y = e.offsety; } }); window.addeventlistener('mouseup', e => { if (isdrawing === true) { drawline(context, x, y, e.offsetx, e.offsety); x = 0; y = 0; isdrawing = false; } }); function drawline(context, x1, y1, x2, y2) { context.beginpath(); context.strokestyle = 'black'; context.linewidth = 1; context.moveto(x1, y1); context.lineto(x2, y2); context.stroke(); context.closepath(); } result specifications specification status ui eventsthe definition of 'mousedown' in that specification.

Element: mousemove event - Web APIs
the mouseup event draws the final line segment, sets x and y to 0, and stops further drawing by setting isdrawing to false.
... html <h1>drawing with mouse events</h1> <canvas id="mypics" width="560" height="360"></canvas> css canvas { border: 1px solid black; width: 560px; height: 360px; } javascript // when true, moving the mouse draws on the canvas let isdrawing = false; let x = 0; let y = 0; const mypics = document.getelementbyid('mypics'); const context = mypics.getcontext('2d'); // event.offsetx, event.offsety gives the (x,y) offset from the edge of the canvas.
...wn', e => { x = e.offsetx; y = e.offsety; isdrawing = true; }); mypics.addeventlistener('mousemove', e => { if (isdrawing === true) { drawline(context, x, y, e.offsetx, e.offsety); x = e.offsetx; y = e.offsety; } }); window.addeventlistener('mouseup', e => { if (isdrawing === true) { drawline(context, x, y, e.offsetx, e.offsety); x = 0; y = 0; isdrawing = false; } }); function drawline(context, x1, y1, x2, y2) { context.beginpath(); context.strokestyle = 'black'; context.linewidth = 1; context.moveto(x1, y1); context.lineto(x2, y2); context.stroke(); context.closepath(); } result specifications specification status ui eventsthe definition of 'mousemove' in that specification.

Element: mouseup event - Web APIs
the mouseup event draws the final line segment, sets x and y to 0, and stops further drawing by setting isdrawing to false.
... html <h1>drawing with mouse events</h1> <canvas id="mypics" width="560" height="360"></canvas> css canvas { border: 1px solid black; width: 560px; height: 360px; } javascript // when true, moving the mouse draws on the canvas let isdrawing = false; let x = 0; let y = 0; const mypics = document.getelementbyid('mypics'); const context = mypics.getcontext('2d'); // event.offsetx, event.offsety gives the (x,y) offset from the edge of the canvas.
...wn', e => { x = e.offsetx; y = e.offsety; isdrawing = true; }); mypics.addeventlistener('mousemove', e => { if (isdrawing === true) { drawline(context, x, y, e.offsetx, e.offsety); x = e.offsetx; y = e.offsety; } }); window.addeventlistener('mouseup', e => { if (isdrawing === true) { drawline(context, x, y, e.offsetx, e.offsety); x = 0; y = 0; isdrawing = false; } }); function drawline(context, x1, y1, x2, y2) { context.beginpath(); context.strokestyle = 'black'; context.linewidth = 1; context.moveto(x1, y1); context.lineto(x2, y2); context.stroke(); context.closepath(); } result specifications specification status ui eventsthe definition of 'mouseup' in that specification.

Element.setCapture() - Web APIs
syntax element.setcapture(retargettoelement); retargettoelement if true, all events are targeted directly to this element; if false, events can also fire at descendants of this element.
...<head> <title>mouse capture example</title> <style type="text/css"> #mybutton { border: solid black 1px; color: black; padding: 2px; box-shadow: black 2px 2px; } </style> <script type="text/javascript"> function init() { var btn = document.getelementbyid("mybutton"); if (btn.setcapture) { btn.addeventlistener("mousedown", mousedown, false); btn.addeventlistener("mouseup", mouseup, false); } else { document.getelementbyid("output").innerhtml = "sorry, there appears to be no setcapture support on this browser"; } } function mousedown(e) { e.target.setcapture(); e.target.addeventlistener("mousemove", mousemoved, false); } function mouseup(e) { e.target.removeev...
...entlistener("mousemove", mousemoved, false); } function mousemoved(e) { var output = document.getelementbyid("output"); output.innerhtml = "position: " + e.clientx + ", " + e.clienty; } </script> </head> <body onload="init()"> <p>this is an example of how to use mouse capture on elements in gecko 2.0.</p> <p><a id="mybutton" href="#">test me</a></p> <div id="output">no events yet</div> </body> </html> view live examples notes the element may not be scrolled completely to the top or bottom, depending on the layout of other elements.

Event.eventPhase - Web APIs
if event.bubbles is false, processing the event is finished after this phase is complete.
...id="chcapture" /> <label for="chcapture">use capturing</label> <div id="d1">d1 <div id="d2">d2 <div id="d3">d3 <div id="d4">d4</div> </div> </div> </div> <div id="divinfo"></div> css div { margin: 20px; padding: 4px; border: thin black solid; } #divinfo { margin: 18px; padding: 8px; background-color:white; font-size:80%; } javascript let clear = false, divinfo = null, divs = null, usecapture = false; window.onload = function () { divinfo = document.getelementbyid('divinfo') divs = document.getelementsbytagname('div') chcapture = document.getelementbyid('chcapture') chcapture.onclick = function () { removelisteners() addlisteners() } clear() addlisteners() } function removelisteners() { for (let i = 0; i < ...
...divs.length; i++) { let d = divs[i] if (d.id != "divinfo") { d.removeeventlistener("click", ondivclick, true) d.removeeventlistener("click", ondivclick, false) } } } function addlisteners() { for (let i = 0; i < divs.length; i++) { let d = divs[i] if (d.id != "divinfo") { if (chcapture.checked) { d.addeventlistener("click", ondivclick, true) } else { d.addeventlistener("click", ondivclick, false) d.onmousemove = function () { clear = true } } } } } function ondivclick(e) { if (clear) { clear() clear = false } if (e.eventphase == 2) e.currenttarget.style.backgroundcolor = 'red'; let level = e.eventphase == 0 ?

FormDataEvent() - Web APIs
the default is false.
...the default is false.
...the default is false.

Fullscreen API - Web APIs
this is false if full-screen mode is not available for any reason (such as the "fullscreen" feature not being allowed, or full-screen mode not being supported).
... obsolete properties document.fullscreen a boolean value which is true if the document has an element currently being displayed in full-screen mode; otherwise, this returns false.
... document.addeventlistener("keypress", function(e) { if (e.keycode === 13) { togglefullscreen(); } }, false); toggling full-screen mode this code is called by the event handler above when the user hits the enter key.

Using the Gamepad API - Web APIs
var gamepads = {}; function gamepadhandler(event, connecting) { var gamepad = event.gamepad; // note: // gamepad === navigator.getgamepads()[gamepad.index] if (connecting) { gamepads[gamepad.index] = gamepad; } else { delete gamepads[gamepad.index]; } } window.addeventlistener("gamepadconnected", function(e) { gamepadhandler(e, true); }, false); window.addeventlistener("gamepaddisconnected", function(e) { gamepadhandler(e, false); }, false); this previous example also demonstrates how the gamepad property can be held after the event has completed — a technique we will use for device state querying later.
...if this is so the value is true; if not, it is false.
...each gamepadbutton has a pressed and a value property: the pressed property is a boolean indicating whether the button is currently pressed (true) or unpressed (false).

HTMLElement.hidden - Web APIs
the htmlelement property hidden is a boolean which is true if the element is hidden; otherwise the value is false.
... syntax ishidden = htmlelement.hidden; htmlelement.hidden = true | false; value a boolean which is true if the element is hidden from view; otherwise, the value is false.
... javascript document.getelementbyid("okbutton") .addeventlistener("click", function() { document.getelementbyid("welcome").hidden = true; document.getelementbyid("awesome").hidden = false; }, false); this code sets up a handler for the welcome panel's "ok" button that hides the welcome panel and makes the follow-up panel—with the curious name "awesome"—visible in its place.

HTMLFormElement - Web APIs
checkvalidity() returns true if the element's child controls are subject to constraint validation and satisfy those contraints; returns false if some controls do not satisfy their constraints.
...it is up to the programmer to decide how to respond to false.
...when false is returned, cancelable invalid events are fired for each invalid child and validation problems are reported to the user.

HTMLImageElement.complete - Web APIs
syntax let doneloading = htmlimageelement.complete; value a boolean value which is true if the image has completely loaded; otherwise, the value is false.
...= lightboxelem.queryselector(".toolbar"); async function loadimage(url, elem) { return new promise((resolve, reject) => { elem.onload = () => resolve(elem); elem.onerror = reject; elem.src = url; }); } async function lightbox(url) { lightboxelem.style.display = "block"; await loadimage("https://somesite.net/huge-image.jpg", lightboximgelem); lightboxcontrolselem.disabled = false; } /* ...
... for androidsafari on iossamsung internetcompletechrome full support 1edge full support 12firefox full support yesie full support 8notes full support 8notes notes ie reports false for broken images.opera full support yessafari full support yeswebview android full support yeschrome android full support yesfirefox android full support yesopera android ...

HTMLMediaElement: play event - Web APIs
the play event is fired when the paused property is changed from true to false, as a result of the play method, or the autoplay attribute.
... using addeventlistener(): const video = document.queryselector('video'); video.addeventlistener('play', (event) => { console.log('the boolean paused property is now false.
... either the ' + 'play() method was called or the autoplay attribute was toggled.'); }); using the onplay event handler property: const video = document.queryselector('video'); video.onplay = (event) => { console.log('the boolean paused property is now false.

HTMLMediaElement - Web APIs
true if the audio is muted and false otherwise.
...if set to false, the pitch will adjust to the speed of the audio.
... play fired when the paused property is changed from true to false, as a result of the htmlmediaelement.play() method, or the autoplay attribute playing fired when playback is ready to start after having been paused or delayed due to lack of data progress fired periodically as the browser loads a resource.

Option() - Web APIs
if this is not specified, a default value of false is used.
... selected optional a boolean that sets the option's selected state; the default is false (not selected).
...nd options with different parameters /* assuming we have the following html <select id="s"> <option>first</option> <option>second</option> <option>third</option> </select> */ var s = document.getelementbyid('s'); var options = [ 'zero', 'one', 'two' ]; options.foreach(function(element, key) { if (element == 'zero') { s[s.options.length] = new option(element, s.options.length, false, false); } if (element == 'one') { s[s.options.length] = new option(element, s.options.length, true, false); // will add the "selected" attribute } if (element == 'two') { s[s.options.length] = new option(element, s.options.length, false, true); // just will be selected in "view" } }); /* result <select id="s"> <option value="0">zero</option> <option value="1" selected="">o...

IDBIndex.multiEntry - Web APIs
this method takes an optional options parameter whose multientry property is set to true/false.
... false there is one record for each key that is an array.
... the multi-entry status of the index is logged to the console: it should be returned as false.

MediaCapabilitiesInfo - Web APIs
otherwise, it is false.
... if supported is true, and playback will be smooth, smooth is true, otherwise, is it false.
...if supported is true, and playback will be power efficient, powerefficient is true, otherwise, is it false.

active - Web APIs
the active read-only property of the mediastream interface returns a boolean value which is true if the stream is currently active; otherwise, it returns false.
...once every track has ended, the stream's active property becomes false.
... syntax var isactive = mediastream.active; value a boolean value which is true if the stream is currently active; otherwise, the value is false.

MutationObserverInit.attributes - Web APIs
syntax var options = { attributes: true | false } value a boolean value indicating whether or not to report through the callback any changes to the values of attributes on the node or nodes being monitored.
... the default value is false.
... subtree lets you specify whether to watch the target node and all of its descendants (true), or just the target node (false).

MutationObserverInit.childList - Web APIs
if childlist is false (the default), adding or removing new nodes does not trigger mutation callbacks.
... syntax var options = { childlist: true | false } value a boolean value indicating whether or not to invoke the callback function when new nodes are added to or removed from the section of the dom being monitored..
... if subtree is false, only the node indicated by the observer's target node is monitored for changes.

Notification.Notification() - Web APIs
the default is false, which means they won't be notified.
...the default value is false.
...the default is false, which means it won't be silent.

PointerEvent.isPrimary - Web APIs
it returns true if the pointer that caused the event to be fired is the primary device and returns false otherwise.
... syntax var isprimary = pointerevent.isprimary; return value isprimary returns true if the pointer for this event is the primary pointer and returns false otherwise.
... target.addeventlistener('pointerdown', function(event) { if (event.isprimary) process_primary_pointer(event); else process_secondary_pointer(event); }, false); specifications specification status comment pointer events – level 2the definition of 'isprimary' in that specification.

Multi-touch interaction - Web APIs
// log events flag var logevents = false; // event caches, one per touch target var evcache1 = new array(); var evcache2 = new array(); var evcache3 = new array(); register event handlers event handlers are registered for the following pointer events: pointerdown, pointermove and pointerup.
... // log events flag var logevents = false; function enablelog(ev) { logevents = logevents ?
... false : true; } function log(name, ev) { var o = document.getelementsbytagname('output')[0]; var s = name + ": pointerid = " + ev.pointerid + " ; pointertype = " + ev.pointertype + " ; isprimary = " + ev.isprimary; o.innerhtml += s + " "; } function clearlog(event) { var o = document.getelementsbytagname('output')[0]; o.innerhtml = ""; } ...

RTCPeerConnection.createDataChannel() - Web APIs
t dictionary provides the following fields, any of which may be included in the object passed as the options parameter in order to configure the data channel to suit your needs: ordered optional indicates whether or not messages sent on the rtcdatachannel are required to arrive at their destination in the same order in which they were sent (true), or if they're allowed to arrive out-of-order (false).
... negotiated optional by default (false), data channels are negotiated in-band, where one side calls createdatachannel, and the other side listens to the rtcdatachannelevent event using the ondatachannel eventhandler .
...default: false.

Range.collapse() - Web APIs
syntax range.collapse(tostart); parameters tostart optional a boolean value: true collapses the range to its start, false to its end.
... if omitted, it defaults to false .
... living standard the parameter is now optional and default to false.

SpeechRecognition.continuous - Web APIs
it defaults to single results (false.) syntax var mycontinuous = myspeechrecognition.continuous; myspeechrecognition.continuous = true; value a boolean representing the current speechrecognition's continuous status.
... true means continuous, and false means not continuous (single result each time.) examples this code is excerpted from our speech color changer example.
...occasin | navy | olive | orange | orchid | peru | pink | plum | purple | red | salmon | sienna | silver | snow | tan | teal | thistle | tomato | turquoise | violet | white | yellow ;' var recognition = new speechrecognition(); var speechrecognitionlist = new speechgrammarlist(); speechrecognitionlist.addfromstring(grammar, 1); recognition.grammars = speechrecognitionlist; recognition.continuous = false; recognition.lang = 'en-us'; recognition.interimresults = false; recognition.maxalternatives = 1; ...

SpeechRecognition - Web APIs
defaults to single (false.) speechrecognition.interimresults controls whether interim results should be returned (true) or not (false.) interim results are results that are not yet final (e.g.
... the speechrecognitionresult.isfinal property is false.) speechrecognition.maxalternatives sets the maximum number of speechrecognitionalternatives provided per result.
...occasin | navy | olive | orange | orchid | peru | pink | plum | purple | red | salmon | sienna | silver | snow | tan | teal | thistle | tomato | turquoise | violet | white | yellow ;' var recognition = new speechrecognition(); var speechrecognitionlist = new speechgrammarlist(); speechrecognitionlist.addfromstring(grammar, 1); recognition.grammars = speechrecognitionlist; recognition.continuous = false; recognition.lang = 'en-us'; recognition.interimresults = false; recognition.maxalternatives = 1; var diagnostic = document.queryselector('.output'); var bg = document.queryselector('html'); document.body.onclick = function() { recognition.start(); console.log('ready to receive a color command.'); } recognition.onresult = function(event) { var color = event.results[0][0].transcript; di...

SubtleCrypto.deriveKey() - Web APIs
/* derive an aes key, given: - our ecdh private key - their ecdh public key */ function derivesecretkey(privatekey, publickey) { return window.crypto.subtle.derivekey( { name: "ecdh", public: publickey }, privatekey, { name: "aes-gcm", length: 256 }, false, ["encrypt", "decrypt"] ); } async function agreesharedsecretkey() { // generate 2 ecdh key pairs: one for alice and one for bob // in more normal usage, they would generate their key pairs // separately and exchange public keys securely let aliceskeypair = await window.crypto.subtle.generatekey( { name: "ecdh", namedcurve: "p-384" }, false, ["derivekey"...
...] ); let bobskeypair = await window.crypto.subtle.generatekey( { name: "ecdh", namedcurve: "p-384" }, false, ["derivekey"] ); // alice then generates a secret key using her private key and bob's public key.
...*/ function getkeymaterial() { let password = window.prompt("enter your password"); let enc = new textencoder(); return window.crypto.subtle.importkey( "raw", enc.encode(password), "pbkdf2", false, ["derivebits", "derivekey"] ); } async function encrypt(plaintext, salt, iv) { let keymaterial = await getkeymaterial(); let key = await window.crypto.subtle.derivekey( { "name": "pbkdf2", salt: salt, "iterations": 100000, "hash": "sha-256" }, keymaterial, { "name": "aes-gcm", "length": 256}, true, [ "encrypt", "decrypt" ] ); return...

TouchEvent.altKey - Web APIs
otherwise, it is false.
... syntax var altenabled = touchevent.altkey; return value altenabled true if the alt key is enabled for this event; and false if the alt is not enabled.
... someelement.addeventlistener('touchstart', function(e) { // log the state of this event's modifier keys console.log("altkey = " + e.altkey); console.log("ctrlkey = " + e.ctrlkey); console.log("metakey = " + e.metakey); console.log("shiftkey = " + e.shiftkey); }, false); specifications specification status comment touch events – level 2 draft non-stable version.

TouchEvent.targetTouches - Web APIs
in following code snippet, the function compares the length of the touches list to the the length of the targettouches list and returns true if the lengths are the same and returns false otherwise.
... function touches_in_target(ev) { // return true if all of the touches are within the target element; // otherwise return false.
...true : false); } specifications specification status comment touch events – level 2 draft non-stable version.

WebGLRenderingContext.makeXRCompatible() - Web APIs
javascript the code that handles starting up graphics, switching to vr mode, and so forth looks like this: const outputcanvas = document.queryselector(".output-canvas"); const gl = outputcanvas.getcontext("webgl"); let xrsession = null; let usingxr = false; let currentscene = "scene1"; let glstartbutton; let xrstartbutton; window.addeventlistener("load", (event) => { loadsceneresources(currentscene); glstartbutton.addeventlistener("click", handlestartbuttonclick); xrstartbutton.addeventlistener("click", handlestartbuttonclick); }); outputcanvas.addeventlistener("webglcontextlost", (event) => { /* the context has been lost but can be rest...
..., "cancel"); break; default: handlefatalerror(err); break; } xrsession.end(); } } async function handlestartbuttonclick(event) { if (event.target.classlist.contains("use-webxr") && navigator.xr) { try { xrsession = await navigator.xr.requestsession("immersive-vr"); usingxr = true; } catch(err) { xrsession = null; usingxr = false; } } startgame(); } function startgame() { currentscene = "scene1"; loadsceneresources(currentscene); /* and so on */ } this works by having two buttons, one which starts the game normally and the other which starts the game in vr mode.
... if the other button was clicked, we ensure that xrsession is null and clear usingxr to false.

WebGLRenderingContext.sampleCoverage() - Web APIs
the default value is false.
... gl.enable(gl.sample_coverage); gl.samplecoverage(0.5, false); to check the sample coverage values, query the sample_coverage_value and sample_coverage_invert constants.
... gl.getparameter(gl.sample_coverage_value); // 0.5 gl.getparameter(gl.sample_coverage_invert); // false specifications specification status comment webgl 1.0the definition of 'samplecoverage' in that specification.

Clearing by clicking - Web APIs
window.removeeventlistener(evt.type, setupwebgl, false); // adding the same click event handler to both canvas and // button.
... var canvas = document.queryselector("#canvas-view"); var button = document.queryselector("#color-switcher"); canvas.addeventlistener("click", switchcolor, false); button.addeventlistener("click", switchcolor, false); // a variable to hold the webglrenderingcontext.
... function getrandomcolor() { return [math.random(), math.random(), math.random()]; } }, false); the source code of this example is also available on github.

Color masking - Web APIs
ck; font-family : serif; font-size : inherit; font-weight : 900; color : white; margin : auto; padding : 0.6em 1.2em; } #red-toggle { background-color : red; } #green-toggle { background-color : green; } #blue-toggle { background-color : blue; } window.addeventlistener("load", function setupanimation (evt) { "use strict" window.removeeventlistener(evt.type, setupanimation, false); var canvas = document.queryselector("canvas"); var gl = canvas.getcontext("webgl") || canvas.getcontext("experimental-webgl"); if (!gl) { document.queryselector("p").innerhtml = "failed to get webgl context." + "your browser or device may not support webgl."; return; } gl.viewport(0, 0, gl.drawingbufferwidth, gl.drawingbufferheight); var timer = setin...
...terval(drawanimation, 1000); var mask = [true, true, true]; var redtoggle = document.queryselector("#red-toggle"), greentoggle = document.queryselector("#green-toggle"), bluetoggle = document.queryselector("#blue-toggle"); redtoggle.addeventlistener("click", setcolormask, false); greentoggle.addeventlistener("click", setcolormask, false); bluetoggle.addeventlistener("click", setcolormask, false); function setcolormask(evt) { var index = evt.target === greentoggle && 1 || evt.target === bluetoggle && 2 || 0; mask[index] = !mask[index]; if (mask[index] === true) evt.target.innerhtml="on"; else evt.target.innerhtml="off"; gl.colormask(mask[0], mask[1], mask[2], true); drawanimation(); }; function drawanimation () { ...
... var color = getrandomcolor(); gl.clearcolor(color[0], color[1], color[2], 1.0); gl.clear(gl.color_buffer_bit); } function getrandomcolor() { return [math.random(), math.random(), math.random()]; } }, false); the source code of this example is also available on github.

Scissor animation - Web APIs
does not seem to support html5 canvas.</canvas> body { text-align : center; } canvas { display : block; width : 280px; height : 210px; margin : auto; padding : 0; border : none; background-color : black; } button { display : block; font-size : inherit; margin : auto; padding : 0.6em; } ;(function(){ "use strict" window.addeventlistener("load", setupanimation, false); // variables to hold the webgl context, and the color and // position of animated squares.
... var gl, color = getrandomcolor(), position; function setupanimation (evt) { window.removeeventlistener(evt.type, setupanimation, false); if (!(gl = getrenderingcontext())) return; gl.enable(gl.scissor_test); gl.clearcolor(color[0], color[1], color[2], 1.0); // unlike the browser window, vertical position in webgl is // measured from bottom to top.
... position = [0, gl.drawingbufferheight]; var button = document.queryselector("button"); var timer; function startanimation(evt) { button.removeeventlistener(evt.type, startanimation, false); button.addeventlistener("click", stopanimation, false); document.queryselector("strong").innerhtml = "stop"; timer = setinterval(drawanimation, 17); drawanimation(); } function stopanimation(evt) { button.removeeventlistener(evt.type, stopanimation, false); button.addeventlistener("click", startanimation, false); document.queryselector("strong").innerhtml = "start"; clearinterval(timer); } stopanimation({type: "click"}); } // variables to hold ...

Adding 2D content to a WebGL context - Web APIs
if that's false, we know the shader failed to compile, so show an alert with log information obtained from the compiler using gl.getshaderinfolog(), then delete the shader and return null to indicate a failure to load the shader.
... { const numcomponents = 2; // pull out 2 values per iteration const type = gl.float; // the data in the buffer is 32bit floats const normalize = false; // don't normalize const stride = 0; // how many bytes to get from one set of values to the next // 0 = use type and numcomponents above const offset = 0; // how many bytes inside the buffer to start from gl.bindbuffer(gl.array_buffer, buffers.position); gl.vertexattribpointer( programinfo.attriblocations.vertexposition, ...
... numcomponents, type, normalize, stride, offset); gl.enablevertexattribarray( programinfo.attriblocations.vertexposition); } // tell webgl to use our program when drawing gl.useprogram(programinfo.program); // set the shader uniforms gl.uniformmatrix4fv( programinfo.uniformlocations.projectionmatrix, false, projectionmatrix); gl.uniformmatrix4fv( programinfo.uniformlocations.modelviewmatrix, false, modelviewmatrix); { const offset = 0; const vertexcount = 4; gl.drawarrays(gl.triangle_strip, offset, vertexcount); } } the first step is to clear the canvas to our background color; then we establish the camera's perspective.

Example and tutorial: Simple synth keyboard - Web APIs
function setup() { notefreq = createnotetable(); volumecontrol.addeventlistener("change", changevolume, false); mastergainnode = audiocontext.creategain(); mastergainnode.connect(audiocontext.destination); mastergainnode.gain.value = volumecontrol.value; // create the keys; skip any that are sharp or flat; for // our purposes we don't need them.
... let keylist = object.entries(keys); let octaveelem = document.createelement("div"); octaveelem.classname = "octave"; keylist.foreach(function(key) { if (key[0].length == 1) { octaveelem.appendchild(createkey(key[0], idx, key[1])); } }); keyboard.appendchild(octaveelem); }); document.queryselector("div[data-note='b'][data-octave='5']").scrollintoview(false); sineterms = new float32array([0, 0, 1, 0, 1]); cosineterms = new float32array(sineterms.length); customwaveform = audiocontext.createperiodicwave(cosineterms, sineterms); for (i=0; i<9; i++) { osclist[i] = []; } } setup(); the table which maps note names and octaves to their frequenies is created by calling createnotetable().
... = document.createelement("div"); let labelelement = document.createelement("div"); keyelement.classname = "key"; keyelement.dataset["octave"] = octave; keyelement.dataset["note"] = note; keyelement.dataset["frequency"] = freq; labelelement.innerhtml = note + "_{" + octave + "}"; keyelement.appendchild(labelelement); keyelement.addeventlistener("mousedown", notepressed, false); keyelement.addeventlistener("mouseup", notereleased, false); keyelement.addeventlistener("mouseover", notepressed, false); keyelement.addeventlistener("mouseleave", notereleased, false); return keyelement; } after creating the elements that will represent the key and its label, we configure the key's element by setting its class to "key" (which establishes its appearance).

window.postMessage() - Web APIs
the dispatched event otherwindow can listen for dispatched messages by executing the following javascript: window.addeventlistener("message", receivemessage, false); function receivemessage(event) { if (event.origin !== "http://example.org:8080") return; // ...
... the secret response is: rheeeeet!" } window.addeventlistener("message", receivemessage, false); /* * in the popup's scripts, running on <http://example.com>: */ // called sometime after postmessage is called function receivemessage(event) { // do we trust the sender of this message?
... the secret response " + "is: rheeeeet!", event.origin); } window.addeventlistener("message", receivemessage, false); notes any window may access this method on any other window, at any time, regardless of the location of the document in the window, to send it a message.

HTML in XMLHttpRequest - Web APIs
function htmlinxhr() { if (!window.xmlhttprequest) return false; var req = new window.xmlhttprequest(); req.open('get', window.location.href, false); try { req.responsetype = 'document'; } catch(e) { return true; } return false; } view on jsfiddle this method is synchronous, does not rely on external assets though it may not be as reliable as method 2 described below since it does not check the actual feature but an indication of that ...
...this test file is small and is not well-formed xml: <title>&amp;&<</title> if the file is named detect.html, the following function can be used for detecting html parsing support: function detecthtmlinxhr(callback) { if (!window.xmlhttprequest) { window.settimeout(function() { callback(false); }, 0); return; } var done = false; var xhr = new window.xmlhttprequest(); xhr.onreadystatechange = function() { if (this.readystate == 4 && !done) { done = true; callback(!!(this.responsexml && this.responsexml.title && this.responsexml.title == "&&<")); } } xhr.onabort = xhr.onerror = function() { if (!done) { done = true; callback(false); ...
... } } try { xhr.open("get", "detect.html"); xhr.responsetype = "document"; xhr.send(); } catch (e) { window.settimeout(function() { if (!done) { done = true; callback(false); } }, 0); } } the argument callback is a function that will be called asynchronously with true as the only argument if html parsing is supported and false as the only argument if html parsing is not supported.

Sending and Receiving Binary Data - Web APIs
function load_binary_resource(url) { var req = new xmlhttprequest(); req.open('get', url, false); //xhr binary charset opt by marcus granado 2006 [http://mgran.blogspot.com] req.overridemimetype('text\/plain; charset=x-user-defined'); req.send(null); if (req.status != 200) return ''; return req.responsetext; } the magic happens in line 5, which overrides the mime type, forcing the browser to treat it as plain text, using a user-defined character set.
... var myarray = new arraybuffer(512); var longint8view = new uint8array(myarray); // generate some data for (var i=0; i< longint8view.length; i++) { longint8view[i] = i % 256; } var xhr = new xmlhttprequest; xhr.open("post", url, false); xhr.send(myarray); this is building a 512-byte array of 8-bit integers and sending it; you can use any binary data you'd like, of course.
...s["@mozilla.org/mime;1"] .getservice(components.interfaces.nsimimeservice); mimetype = mimeservice.gettypefromfile(file); // file is an nsifile instance } catch (oevent) { /* eat it; just use text/plain */ } // send var req = components.classes["@mozilla.org/xmlextras/xmlhttprequest;1"] .createinstance(components.interfaces.nsixmlhttprequest); req.open('put', url, false); /* synchronous!

XRPose.emulatedPosition - Web APIs
if the position is precisely gbased on direct sensor inputs, the value is false.
... contrariwise, xr devices which can also track movement forward and backward as well as laterally—six degree of freedom (6dof) devices—don't require any information from other sources to determine the user's position, so the value of emulatedposition is false.
...a hand controller that can directly report its position would have a value of false for this property as well.

XRSystem: isSessionSupported() - Web APIs
otherwise, the promise resolves with false.
... return value a promise that resolves to true if the specified session mode is supported; otherwise the promise resolves to false.
... if (navigator.xr) { navigator.xr.issessionsupported('immersive-vr') .then((issupported) => { if (issupported) { userbutton.addeventlistener('click', onbuttonclicked); userbutton.innerhtml = 'enter xr'; userbutton.disabled = false; } }); } function onbuttonclicked() { if (!xrsession) { navigator.xr.requestsession('immersive-vr') .then((session) => { xrsession = session; // onsessionstarted() not shown for reasons of brevity and clarity.

XRView.eye - Web APIs
gllayer = xrsession.renderstate.baselayer; gl.bindframebuffer(gl.framebuffer, gllayer.framebuffer); gl.clearcolor(0,0, 0, 1.0); gl.cleardepth(1.0); gl.clear(gl.color_buffer_bit, gl.depth_buffer_bit); for (let view of xrpose.views) { let skipview = false; if (view.eye == "left" && body.lefteye.injured) || skipview = updateinjury(body.lefteye); } else if (view.eye == "right" && body.righteye.injured) { skipview = updateinjury(body.righteye); } if (!skipview) { let viewport = gllayer.getviewport(view); gl.viewport(viewport.x, viewport.y, viewport.width, viewport.height); renderscene(gl, view); } } for each of the vi...
... updateinjury() returns true if the eye is still injured or false if the eye has been restored to health by the function,.
... if the result is false, indicating that the eye is now healthy, we render the scene for that eye.

XRWebGLLayer() - Web APIs
antialias optional a boolean value which is true if anti-aliasing is to be used when rendering in the context; otherwise false.
...the default is false.
...the default is false.

XRWebGLLayer.ignoreDepthValues - Web APIs
if the depth buffer is being used to determine the position of vertices, this property is false.
...since the xr compositor uses the depth buffer by default, this value is false unless explicitly set otherwise when creating the xrwebgllayer using its constructor, xrwebgllayer().
... usage notes when the ignoredepthvalues property is false, the xr compositor uses the values found in the depth buffer, which should be accurate for the scene, in order to potentially improve the quality or the output as well as the comfort level for the viewer.

XRWebGLLayerInit.depth - Web APIs
when using the xrwebgllayer() constructor to create a new webgl rendering layer for webxr, providing as the layerinit parameter an object whose depth property is false will request that the new layer be created without a depth buffer.
... syntax let layerinit = { depth: false }; let gllayer = new xrwebgllayer(xrsession, gl, layerinit); let gllayer = new xrwebgllayer(xrsession, gl, { depth: false }); value a boolean which can be set to false to specify that the new webgl layer should not have a depth buffer.
... xrsession.updaterenderstate({ baselayer: new xrwebgllayer(xrsession, gl, { depth: false }); }); specifications specification status comment webxr device apithe definition of 'xrwebgllayerinit.depth' in that specification.

XRWebGLLayerInit.stencil - Web APIs
when using the xrwebgllayer() constructor to create a new webgl rendering layer for webxr, providing as the layerinit parameter an object whose stencil property is false requests that the new layer be created without a stencil buffer.
... syntax let layerinit = { stencil: false }; let gllayer = new xrwebgllayer(xrsession, gl, layerinit); let gllayer = new xrwebgllayer(xrsession, gl, { stencil: false }); value a boolean which can be set to false to specify that the new webgl layer should not include a stencil buffer.
... xrsession.updaterenderstate({ baselayer: new xrwebgllayer(xrsession, gl, { stencil: false }); }); specifications specification status comment webxr device apithe definition of 'xrwebgllayerinit.stencil' in that specification.

XRWebGLLayerInit - Web APIs
antialias optional a boolean value which is true if anti-aliasing is to be used when rendering in the context; otherwise false.
...the default is false.
...the default is false.

ARIA live regions - Accessibility
the possible settings are: false or true.
... the default setting is false.
... aria-atomic is not set (false by default) so that only the added or removed users should be spoken and not the entire roster each time.

Using the aria-hidden attribute - Accessibility
using aria-hidden="false" will not re-expose the element to assistive technology if any of its parents specify aria-hidden="true".
... wai-aria authoring practices 1.1 notes that aria-hidden="false" currently behaves inconsistently across browsers.
... values false (default) the element is exposed to the accessibility api.

Basic form hints - Accessibility
<h3 id="rg1_label">lunch options</h3> <ul class="radiogroup" id="rg1" role="radiogroup" aria-labelledby="rg1_label"> <li id="r1" tabindex="-1" role="radio" aria-checked="false"> <img role="presentation" src="radio-unchecked.gif" /> thai </li> <li id="r2" tabindex="-1" role="radio" aria-checked="false"> <img role="presentation" src="radio-unchecked.gif" /> subway </li> <li id="r3" tabindex="0" role="radio" aria-checked="true"> <img role="presentation" src="radio-checked.gif" /> radio maria </li> </ul> describing with aria form controls somet...
... <form> <div> <label for="name">* name:</label> <input type="text" value="name" id="name" aria-required="true"/> </div> <div> <label for="phone">phone:</label> <input type="text" value="phone" id="phone" aria-required="false"/> </div> <div> <label for="email">* e-mail:</label> <input type="text" value="email" id="email" aria-required="true"/> </div> </form> the script that validates the form entry would look something like this: var validate = function () { var emailelement = document.getelementbyid(emailfieldid); var valid = emailvalid(formdata.email); // returns true if valid, false otherwise ...
... emailelement.setattribute("aria-invalid", !valid); setelementbordercolour(emailelement, valid); // sets the border to red if second arg is false }; providing helpful error messages read how to use aria alerts to enhance forms.

Cross-browser audio basics - Developer guides
type="audio/mpeg"> <source src="audiofile.ogg" type="audio/ogg"> <!-- fallback for non supporting browsers goes here --> <a href="audiofile.mp3">download audio</a> <object width="320" height="30" type="application/x-shockwave-flash" data="mediaelement-flash-video.swf"> <param name="movie" value="mediaelement-flash-video.swf" /> <param name="flashvars" value="controls=true&isvideo=false&file=audiofile.mp3" /> </object> </audio> note: you should be aware that flash and silverlight code require that the user has the appropriate plugin installed, and that the browser cannot guarantee the security aspects of code running on those plugin platforms.
...} canplaytype() returns one of three values: probably maybe "" (an empty string) in practice, we usually check if the result is true or false.
... seeked seeked occurs when the seeking attribute changes to false.

Video player styling basics - Developer guides
'unmute' : 'mute'); } } this function is then called by the relevant event handlers: video.addeventlistener('play', function() { changebuttonstate('playpause'); }, false); video.addeventlistener('pause', function() { changebuttonstate('playpause'); }, false); stop.addeventlistener('click', function(e) { video.pause(); video.currenttime = 0; progress.value = 0; // update the play/pause button's 'data-state' which allows the correct button image to be set via css changebuttonstate('playpause'); }); mute.addeventlistener('click', function(e) { v...
... else if (dir === '-') { if (currentvolume > 0) video.volume -= 0.1; } // if the volume has been turned off, also set it as muted // note: can only do this with the custom control set as when the 'volumechange' event is raised, there is no way to know if it was via a volume or a mute change if (currentvolume <= 0) video.muted = true; else video.muted = false; } changebuttonstate('mute'); } var altervolume = function(dir) { checkvolume(dir); } this new checkvolume() function does the same thing as the altervolume() but it also sets the state of the mute button depending on the video's current volume setting.
... checkvolume() is also called when the volumechange event is raised: video.addeventlistener('volumechange', function() { checkvolume(); }, false); progress bar a small change also needs to be made to the click handler for the <progress> element.

Rich-Text Editing in Mozilla - Developer guides
figure 4 : executing rich editing commands html: <button onclick="doricheditcommand('bold')" style="font-weight:bold;">b</button> javascript: function doricheditcommand(aname, aarg){ getiframedocument('editorwindow').execcommand(aname,false, aarg); document.getelementbyid('editorwindow').contentwindow.focus() } example: a simple but complete rich text editor <!doctype html> <html> <head> <title>rich text editor</title> <script type="text/javascript"> var odoc, sdeftxt; function initdoc() { odoc = document.getelementbyid("textbox"); sdeftxt = odoc.innerhtml; if (document.compform.switchmode.checked) { setdocmode(true); }...
... } function formatdoc(scmd, svalue) { if (validatemode()) { document.execcommand(scmd, false, svalue); odoc.focus(); } } function validatemode() { if (!document.compform.switchmode.checked) { return true ; } alert("uncheck \"show html\"."); odoc.focus(); return false; } function setdocmode(btosource) { var ocontent; if (btosource) { ocontent = document.createtextnode(odoc.innerhtml); odoc.innerhtml = ""; var opre = document.createelement("pre"); odoc.contenteditable = false; opre.id = "sourcetext"; opre.contenteditable = true; opre.appendchild(ocontent); odoc.appendchild(opre); } else { if (document.all) { odoc.innerhtml = odoc.innertext; } else { ocontent = document.createrange(); ocontent.selectnodecontents(odoc.firs...
...px; height: 200px; border: 1px #000000 solid; padding: 12px; overflow: scroll; } #textbox #sourcetext { padding: 0; margin: 0; min-width: 498px; min-height: 200px; } #editmode label { cursor: pointer; } </style> </head> <body onload="initdoc();"> <form name="compform" method="post" action="sample.php" onsubmit="if(validatemode()){this.mydoc.value=odoc.innerhtml;return true;}return false;"> <input type="hidden" name="mydoc"> <div id="toolbar1"> <select onchange="formatdoc('formatblock',this[this.selectedindex].value);this.selectedindex=0;"> <option selected>- formatting -</option> <option value="h1">title 1 &lt;h1&gt;</option> <option value="h2">title 2 &lt;h2&gt;</option> <option value="h3">title 3 &lt;h3&gt;</option> <option value="h4">title 4 &lt;h4&gt;</option> <option value=...

draggable - HTML: Hypertext Markup Language
false: the element cannot be dragged.
...a value of true or false is mandatory, and shorthand like <img draggable> is forbidden.
... the correct usage is <img draggable="false">.

Global attributes - HTML: Hypertext Markup Language
the attribute must take one of the following values: true or the empty string, which indicates that the element must be editable; false, which indicates that the element must not be editable.
...it can have the following values: true, which indicates that the element may be dragged false, which indicates that the element may not be dragged.
...it may have the following values: true, which indicates that the element should be, if possible, checked for spelling errors; false, which indicates that the element should not be checked for spelling errors.

Details of the object model - JavaScript
note: this may not work as expected if the constructor function is called with arguments which convert to false (like 0 (zero) and empty string ("").
..._.__proto__ == null; given this, you could write an instanceof function as follows: function instanceof(object, constructor) { object = object.__proto__; while (object != null) { if (object == constructor.prototype) return true; if (typeof object == 'xml') { return constructor.prototype == xml.prototype; } object = object.__proto__; } return false; } note: the implementation above checks the type of the object against "xml" in order to work around a quirk of how xml objects are represented in recent versions of javascript.
... using the instanceof function defined above, these expressions are true: instanceof(chris, engineer) instanceof(chris, workerbee) instanceof(chris, employee) instanceof(chris, object) but the following expression is false: instanceof(chris, salesperson) global information in constructors when you create constructors, you need to be careful if you set global information in the constructor.

Indexed collections - JavaScript
the simplest way to do this is as follows: let colors = ['red', 'green', 'blue'] for (let i = 0; i < colors.length; i++) { console.log(colors[i]) } if you know that none of the elements in your array evaluate to false in a boolean context—if your array consists only of dom nodes, for example—you can use a more efficient idiom: let divs = document.getelementsbytagname('div') for (let i = 0, div; div = divs[i]; i++) { /* process div in some way */ } this avoids the overhead of checking the length of the array, and ensures that the div variable is reassigned to the current item each time around the loop ...
... function isnumber(value) { return typeof value === 'number' } let a1 = [1, 2, 3] console.log(a1.every(isnumber)) // logs true let a2 = [1, '2', 3] console.log(a2.every(isnumber)) // logs false some(callback[, thisobject]) returns true if callback returns true for at least one item in the array.
... function isnumber(value) { return typeof value === 'number' } let a1 = [1, 2, 3] console.log(a1.some(isnumber)) // logs true let a2 = [1, '2', 3] console.log(a2.some(isnumber)) // logs true let a3 = ['1', '2', '3'] console.log(a3.some(isnumber)) // logs false reduce(callback[, initialvalue]) applies callback(accumulator, currentvalue[, currentindex[, array]]) for each value in the array for the purpose of reducing the list of items down to a single value.

Meta programming - JavaScript
handler.preventextensions() object.preventextensions() reflect.preventextensions() object.preventextensions(proxy) only returns true if object.isextensible(proxy) is false.
... in strict mode, a false value returned from the defineproperty handler will throw a typeerror exception.
... in strict mode, a false return value from the set handler will throw a typeerror exception.

Array.prototype.filter() - JavaScript
return true to keep the element, false otherwise.
...isbigenough(value) { return value >= 10 } let filtered = [12, 5, 8, 130, 44].filter(isbigenough) // filtered is [12, 130, 44] find all prime numbers in an array the following example returns all prime numbers in the array: const array = [-3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]; function isprime(num) { for (let i = 2; num > i; i++) { if (num % i == 0) { return false; } } return num > 1; } console.log(array.filter(isprime)); // [2, 3, 5, 7, 11, 13] filtering invalid entries from json the following example uses filter() to create a filtered json of all elements with non-zero, numeric id.
... let arr = [ { id: 15 }, { id: -1 }, { id: 0 }, { id: 3 }, { id: 12.2 }, { }, { id: null }, { id: nan }, { id: 'undefined' } ] let invalidentries = 0 function filterbyid(item) { if (number.isfinite(item.id) && item.id !== 0) { return true } invalidentries++ return false; } let arrbyid = arr.filter(filterbyid) console.log('filtered array\n', arrbyid) // filtered array // [{ id: 15 }, { id: -1 }, { id: 3 }, { id: 12.2 }] console.log('number of invalid entries = ', invalidentries) // number of invalid entries = 5 searching in array following example uses filter() to filter array content based on search criteria.

Date.prototype.toLocaleString() - JavaScript
to check whether an implementation supports them already, you can use the requirement that illegal language tags are rejected with a rangeerror exception: function tolocalestringsupportslocales() { try { new date().tolocalestring('i'); } catch (e) { return e instanceof rangeerror; } return false; } using locales this example shows some of the variations in localized date and time formats.
...dezember 2012" // an application may want to use utc and make that visible options.timezone = 'utc'; options.timezonename = 'short'; console.log(date.tolocalestring('en-us', options)); // → "thursday, december 20, 2012, gmt" // sometimes even the us needs 24-hour time console.log(date.tolocalestring('en-us', { hour12: false })); // → "12/19/2012, 19:00:00" avoid comparing formatted date values to static values most of the time, the formatting returned by tolocalestring() is consistent.
... for this reason, you cannot expect to be able to compare the results of tolocalestring() to a static value: "1/1/2019, 01:00:00" === new date("2019-01-01t01:00:00z").tolocalestring("en-us"); // true in firefox and others // false in ie and edge note: see also this stackoverflow thread for more details and examples.

NaN - JavaScript
nan === nan; // false number.nan === nan; // false isnan(nan); // true isnan(number.nan); // true number.isnan(nan); // true function valueisnan(v) { return v !== v; } valueisnan(1); // false valueisnan(nan); // true valueisnan(number.nan); // true however, do note the difference between isnan() and number.isnan(): the former will return true if the value is currently nan, or if it is goin...
...g to be nan after it is coerced to a number, while the latter will return true only if the value is currently nan: isnan('hello world'); // true number.isnan('hello world'); // false additionally, some array methods cannot find nan, while others can.
... let arr = [2, 4, nan, 12]; arr.indexof(nan); // -1 (false) arr.includes(nan); // true arr.findindex(n => number.isnan(n)); // 2 specifications specification ecmascript (ecma-262)the definition of 'nan' in that specification.

Number.isInteger() - JavaScript
description if the target value is an integer, return true, otherwise return false.
... if the value is nan or infinity, return false.
... polyfill number.isinteger = number.isinteger || function(value) { return typeof value === 'number' && isfinite(value) && math.floor(value) === value; }; examples using isinteger number.isinteger(0); // true number.isinteger(1); // true number.isinteger(-100000); // true number.isinteger(99999999999999999999999); // true number.isinteger(0.1); // false number.isinteger(math.pi); // false number.isinteger(nan); // false number.isinteger(infinity); // false number.isinteger(-infinity); // false number.isinteger('10'); // false number.isinteger(true); // false number.isinteger(false); // false number.isinteger([1]); // false number.isinteger(5.0); // true number.isinteger(5.000000000000001); // false number.isi...

Number.isNaN() - JavaScript
return value true if the given value is nan and its type is number; otherwise, false.
... description due to both equality operators, == and ===, evaluating to false when checking if nan is nan, the function number.isnan() has become necessary.
...these would have been true with global isnan() number.isnan('nan'); // false number.isnan(undefined); // false number.isnan({}); // false number.isnan('blabla'); // false // these all return false number.isnan(true); number.isnan(null); number.isnan(37); number.isnan('37'); number.isnan('37.37'); number.isnan(''); number.isnan(' '); specifications specification ecmascript (ecma-262)the definition of 'number.isnan' in that specificati...

Object.prototype.constructor - JavaScript
changed new object(), {}, new regexp(), /(?:)/, new string(), 'test' // remains unchanged ] for (let i = 0; i < types.length; i++) { types[i].constructor = type types[i] = [types[i].constructor, types[i] instanceof type, types[i].tostring()] } console.log(types.join('\n')) this example displays the following output (comments added for reference): function type() {},false, // new array() function type() {},false, // [] function type() {},false,false // new boolean() function boolean() { [native code] },false,true // true function type() {},false,mon sep 01 2014 16:03:49 gmt+0600 // new date() function type()...
... {},false,error // new error() function type() {},false,function anonymous() { } // new function() function type() {},false,function () {} // function () {} function type() {},false,[object math] // math function type() {},false,0 // new number() function number() { [native code] },false,1 // 1 function type() {},false,[object object] // new object() function type() {},false,[object object] // {} function type() {},false,/(?:)/ // new regexp() function type() {},false,/(?:)/ ...
... // /(?:)/ function type() {},false, // new string() function string() { [native code] },false,test // 'test' changing the constructor of a function mostly this property is used for defining a function as a function-constructor with further calling it with new and prototype-inherits chain.

Object.create() - JavaScript
e new object's prototype works even better: ocn = object.create( null ); // create "null" object (same as before) object.setprototypeof(ocn, object.prototype); // set new object's prototype to the "generic" object (not standard-object) (in addition to all the string-related functions shown above, this also adds:) > ocn.valueof() // shows {} > ocn.hasownproperty("x") // shows "false" > ocn.constructor // shows "object() { [native code] }" // ...and all the rest of the properties and methods of object.prototype.
...(note that the second parameter // maps keys to *property descriptors*.) o = object.create(object.prototype, { // foo is a regular 'value property' foo: { writable: true, configurable: true, value: 'hello' }, // bar is a getter-and-setter (accessor) property bar: { configurable: false, get: function() { return 10; }, set: function(value) { console.log('setting `o.bar` to', value); } /* with es2015 accessors our code can look like this get() { return 10; }, set(value) { console.log('setting `o.bar` to', value); } */ } }); function constructor() {} o = new constructor(); // is equivalent to: o = object.create(constructor.prototype); // of ...
...o = object.create({}, { p: { value: 42 } }); // by default properties are not writable, // enumerable or configurable: o.p = 24; o.p; // 42 o.q = 12; for (var prop in o) { console.log(prop); } // 'q' delete o.p; // false // to specify an es3 property o2 = object.create({}, { p: { value: 42, writable: true, enumerable: true, configurable: true } }); /* is not equivalent to: this will create an object with prototype : {p: 42 } o2 = object.create({p: 42}) */ specifications specification ecmascript (ecma-262)the definition of 'object.create' in that specification.

Object.prototype.hasOwnProperty() - JavaScript
o = new object(); o.propone = null; o.hasownproperty('propone'); // returns true o.proptwo = undefined; o.hasownproperty('proptwo'); // returns true examples using hasownproperty to test for a property's existence the following example determines whether the o object contains a property named prop: o = new object(); o.hasownproperty('prop'); // returns false o.prop = 'exists'; o.hasownproperty('prop'); // returns true direct vs.
... inherited properties the following example differentiates between direct properties and properties inherited through the prototype chain: o = new object(); o.prop = 'exists'; o.hasownproperty('prop'); // returns true o.hasownproperty('tostring'); // returns false o.hasownproperty('hasownproperty'); // returns false iterating over the properties of an object the following example shows how to iterate over the properties of an object without executing on inherited properties.
...[name]); } else { console.log(name); // tostring or something else } } using hasownproperty as a property name javascript does not protect the property name hasownproperty; thus, if the possibility exists that an object might have a property with this name, it is necessary to use an external hasownproperty to get correct results: var foo = { hasownproperty: function() { return false; }, bar: 'here be dragons' }; foo.hasownproperty('bar'); // always returns false // use another object's hasownproperty // and call it with 'this' set to foo ({}).hasownproperty.call(foo, 'bar'); // true // it's also possible to use the hasownproperty property // from the object prototype for this purpose object.prototype.hasownproperty.call(foo, 'bar'); // true note that in the last cas...

Object.is() - JavaScript
two values are the same if one of the following holds: both undefined both null both true or both false both strings of the same length with the same characters in the same order both the same object (means both object have same reference) both numbers and both +0 both -0 both nan or both non-zero and both not nan and both have the same value this is not the same as being equal according to the == operator.
... the == operator applies various coercions to both sides (if they are not the same type) before testing for equality (resulting in such behavior as "" == false being true), but object.is doesn't coerce either value.
...is) { object.is = function(x, y) { // samevalue algorithm if (x === y) { // steps 1-5, 7-10 // steps 6.b-6.e: +0 != -0 return x !== 0 || 1 / x === 1 / y; } else { // step 6.a: nan == nan return x !== x && y !== y; } }; } examples using object.is object.is('foo', 'foo'); // true object.is(window, window); // true object.is('foo', 'bar'); // false object.is([], []); // false var foo = { a: 1 }; var bar = { a: 1 }; object.is(foo, foo); // true object.is(foo, bar); // false object.is(null, null); // true // special cases object.is(0, -0); // false object.is(-0, -0); // true object.is(nan, 0/0); // true specifications specification ecmascript (ecma-262)...