addObserver
this content is now available at nsiobserverservice.addobserver().

Component; nsIPrefBranch
method overview void addobserver(in string adomain, in nsiobserver aobserver, in boolean aholdweak); void clearuserpref(in string aprefname); void deletebranch(in string astartingat); boolean getboolpref(in string aprefname, requires gecko 54 [optional] in boolean adefaultvalue); string getcharpref(in string aprefname,requires gecko 54 [optional] in string adefaultvalue); requires ge...
... methods addobserver() adds a preference change observer.
...for example, if your observer is registered with addobserver("bar.", ...) on a branch with root "foo.", modifying the preference "foo.bar.baz" will trigger the observer, and adata parameter will be "bar.baz".
...And 4 more matches

nsIPrefBranch2
method overview void addobserver(in string adomain, in nsiobserver aobserver, in boolean aholdweak); void removeobserver(in string adomain, in nsiobserver aobserver); methods addobserver() add a preference change observer.
...for example, if your observer is registered with addobserver("bar.", ...) on a branch with root "foo.", modifying the preference "foo.bar.baz" will trigger the observer, and adata parameter will be "bar.baz".
... void addobserver( in string adomain, in nsiobserver aobserver, in boolean aholdweak ); parameters adomain the preference on which to listen for changes.
...And 3 more matches

Displaying Places information using views
result.addobserver(view.queryinterface(components.interfaces.nsinavhistoryresultobserver)); tree.view = view.queryinterface(components.interfaces.nsitreeview); in fact this is how the built-in tree view works.
...to hook up your view to a nsinavhistoryresult object, you call addobserver() on the result, passing the viewer object which is an instance of nsinavhistoryresultobserver.
...result.addobserver(myview.viewer); more practically, a variation of the code above might be internal to a method on your view.
...And 2 more matches

Preferences - Archive of obsolete content
this interface is described as: // "nsiprefbranch2 allows clients to observe changes to pref values." // this is only necessary prior to gecko 13 if (!("addobserver" in this.branch)) this.branch.queryinterface(components.interfaces.nsiprefbranch2); // finally add the observer.
... 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; case "pref2": // extensions.myextension.pref2 was changed break; } } } myprefobserver.register(); and next, here is a more evolved version of the previous code better fit for code reuse both within a project and across projects (for example, using javascript code modules): /** * @constructor * * @param {string} branch_name * @param {fu...
... */ preflistener.prototype.register = function(trigger) { this._branch.addobserver('', this, false); if (trigger) { let that = this; this._branch.getchildlist('', {}).
...after it's garbage collected, you won't receive notifications anymore, so use the provided examples above, and don't write something like the following code: // don't do this components.classes["@mozilla.org/preferences-service;1"] .getservice(components.interfaces.nsiprefservice) .getbranch("myextension.prefs.") .queryinterface(components.interfaces.nsiprefbranch2) .addobserver("", this, false); using prefhasuservalue() nsiprefbranch.prefhasuservalue(preference) checks whether the preference has been changed from the default value.

XPCOM Objects - Archive of obsolete content
this._prefservice = cc["@mozilla.org/preferences-service;1"].getservice(ci.nsiprefbranch); this._prefvalue = this._prefservice.getboolpref("somepreferencename"); this._prefservice.queryinterface(ci.nsiprefbranch2); this._prefservice.addobserver("somepreferencename", this, false); this._prefservice.queryinterface(ci.nsiprefbranch); this is a common piece of code you'll see when initializing components or jsm that rely on preferences.
...the addobserver method in nsiprefbranch2 is an example of this.
... void addobserver(in string adomain, in nsiobserver aobserver, in boolean aholdweak); luckily, you don't have to do anything special if you want to register your js object as a preference observer.
... this._prefservice.addobserver( "extensions.xulschoolhello.somepref", this, false); }, observe : function(asubject, atopic, adata) { // do stuff here.

Creating JavaScript callbacks in components
here is a very simple example of the observer pattern: [scriptable, uuid(...)] interface stringparserobserver { void onword(string word); }; [scriptable, uuid(...)] interface stringparser { void parse(string data); void addobserver(stringparserobserver observer); }; in this example, the stringparser will call the stringparserobserver.onword method whenever it finishes parsing a word found in the raw string data.
... here is an example of how to use the callback system: var wordhandler = { onword : function(word) { alert(word); } }; var stringparser = /* get a reference to the parser somehow */ stringparser.addobserver(wordhandler); stringparser.parse("pay no attention to the man behind the curtain"); you can find examples of this pattern all over the mozilla codebase.
...so we could convert the example above to accept javascript functions in place of the stringparserobserver by making the following changes: [scriptable, function, uuid(...)] interface stringparserobserver : nsisupports { void onword(string word); }; [scriptable, uuid(...)] interface stringparser { void parse(string data); void addobserver(stringparserobserver observer); }; note the only change was adding function to the interface attributes of the callback interface.
... now we can create a callback javascript function to handle the onword event: function handleword(word) { alert(word); } var stringparser = /* get a reference to the parser somehow */ stringparser.addobserver(handleword); stringparser.parse("pay no attention to the man behind the curtain"); yes, you can still use the normal interface-based callback implementation too.

nsIAnnotationService
notation(in long long aitemid, in autf8string aname); void removepageannotations(in nsiuri auri); void removeitemannotations(in long long aitemid); void copypageannotations(in nsiuri asourceuri, in nsiuri adesturi, in boolean aoverwritedest); void copyitemannotations(in long long asourceitemid, in long long adestitemid, in boolean aoverwritedest); void addobserver(in nsiannotationobserver aobserver); void removeobserver(in nsiannotationobserver aobserver); nsiuri getannotationuri(in nsiuri auri, in autf8string aname); constants constant value description expire_session 0 for temporary data that can be discarded when the user exits.
... addobserver() this method adds an annotation observer.
... void addobserver( in nsiannotationobserver aobserver ); parameters aobserver annotation observer.
... removeobserver() this method removes an annotaton observer previously registered by addobserver() method.

nsINavHistoryResult
method overview void addobserver(in nsinavhistoryresultobserver aobserver, in boolean aownsweak); void removeobserver(in nsinavhistoryresultobserver aobserver); attributes attribute type description root nsinavhistorycontainerresultnode the root of the results.
...obsolete since gecko 2.0 methods addobserver() adds an observer for changes that occur on the result.
... void addobserver( in nsinavhistoryresultobserver aobserver, in boolean aownsweak ); parameters aobserver an object that implements the nsinavhistoryresultobserver interface, which will receive notifications of changes on the result.
... removeobserver() removes an observer that was added by a previous call to addobserver().

Creating Event Targets - Archive of obsolete content
kmarkobserver = { onitemadded: 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.
...vbookmarksservice); var bookmarkobserver = { 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.
... bookmarkobserver = { onitemadded: 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.

Observer Notifications - Archive of obsolete content
adding an observer to the observer service is simple, invoking the addobserver method with three parameters.
... 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.

Common causes of memory leaks in extensions - Extensions
"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.
...you may also specify ownsweak = true in the call to nsiobserverservice.addobserver(), but that might require you to properly implement weak references as well.
...quit-application notifications and unregister your observers from that topic: var myobserver = { observe: function(subject, topic, data) { if (topic == "xpcom-shutdown") { services.obs.removeobserver(myobserver, "private-browsing"); services.obs.removeobserver(myobserver, "xpcom-shutdown"); } else { // do something with "private-browsing" } } }; services.obs.addobserver(myobserver, "private-browsing", false); services.obs.addobserver(myobserver, "xpcom-shutdown", false); finally, a lot of services other than nsiobserverservice accept nsiobserver parameters or other interfaces and will keep strong references around.

nsIContentPrefService
to create an instance, use: var contentprefservice = components.classes["@mozilla.org/content-pref/service;1"] .getservice(components.interfaces.nsicontentprefservice); method overview void addobserver(in astring aname, in nsicontentprefobserver aobserver); nsivariant getpref(in nsivariant agroup, in astring aname, [optional] in nsicontentprefcallback acallback); nsipropertybag2 getprefs(in nsivariant agroup); nsipropertybag2 getprefsbyname(in astring aname); boolean haspref(in nsivariant agroup, in astring aname); void removegroupedprefs(); ...
... methods addobserver() adds an observer that monitors a preference for changes.
... void addobserver( in astring aname, in nsicontentprefobserver aobserver ); parameters aname the name of the preference to observe.

nsIContentPrefService2
method overview void addobserverforname(in astring name, in nsicontentprefobserver observer); void getbydomainandname(in astring domain, in astring name, in nsiloadcontext context, in nsicontentprefcallback2 callback); void getbysubdomainandname(in astring domain, in astring name, in nsiloadcontext context, in nsicontentprefcallback2 callback); nsicontentpref getcachedbydomainandna...
...oid removeobserverforname(in astring name, in nsicontentprefobserver observer); void set(in astring domain, in astring name, in nsivariant value, in nsiloadcontext context, [optional] in nsicontentprefcallback2 callback); void setglobal(in astring name, in nsivariant value, in nsiloadcontext context, [optional] in nsicontentprefcallback2 callback); methods addobserverforname() registers an observer that will be notified whenever a preference with the given name is set() or removed.
...void addobserverforname( in astring name, in nsicontentprefobserver observer ); parameters name the name of the preferences to observe.

nsIMicrosummary
1.0 66 introduced gecko 1.8 obsolete gecko 6.0 inherits from: nsisupports last changed in gecko 1.9 (firefox 3) warning: microsummary support was removed in gecko 6.0 (firefox 6.0 / thunderbird 6.0 / seamonkey 2.3) method overview void addobserver(in nsimicrosummaryobserver observer); boolean equals(in nsimicrosummary aother); void removeobserver(in nsimicrosummaryobserver observer); void update(); attributes attribute type description content astring the content of the microsummary.
... methods addobserver() add a microsummary observer to this microsummary.
... void addobserver( in nsimicrosummaryobserver observer ); parameters observer the microsummary observer to add.