XMLHttpRequest.onreadystatechange - Web APIs
the xmlhttprequest.onreadystatechange property contains the event handler to be called when the readystatechange event is fired, that is every time the readystate property of the xmlhttprequest changes.
... syntax xmlhttprequest.onreadystatechange = callback; values callback is the function to be executed when the readystate changes.
... examples const xhr = new xmlhttprequest(), method = "get", url = "https://developer.mozilla.org/"; xhr.open(method, url, true); xhr.onreadystatechange = function () { // in local files, status is 0 upon success in mozilla firefox if(xhr.readystate === xmlhttprequest.done) { var status = xhr.status; if (status === 0 || (status >= 200 && status < 400)) { // the request has been completed successfully console.log(xhr.responsetext); } else { // oh no!

Getting Started - Developer guides
at this stage, you need to tell the xmlhttp request object which javascript function will handle the response, by setting the onreadystatechange property of the object and naming it after the function to call when the request changes state, like this: httprequest.onreadystatechange = nameofthefunction; note that there are no parentheses or parameters after the function name, because you're assigning a reference to the function, rather than actually calling it.
... alternatively, instead of giving a function name, you can use the javascript technique of defining functions on the fly (called "anonymous functions") to define the actions that will process the response, like this: httprequest.onreadystatechange = function(){ // process the server response here.
...for example, use the following before calling send() for form data sent as a query string: httprequest.setrequestheader('content-type', 'application/x-www-form-urlencoded'); step 2 – handling the server response when you sent the request, you provided the name of a javascript function to handle the response: httprequest.onreadystatechange = nameofthefunction; what should this function do?
...And 4 more matches

Cross-Origin Resource Sharing (CORS) - HTTP
code of this sort might be used in javascript deployed on foo.example: const xhr = new xmlhttprequest(); const url = 'https://bar.other/resources/public-data/'; xhr.open('get', url); xhr.onreadystatechange = somehandler; xhr.send(); this performs a simple exchange between the client and the server, using cors headers to handle the privileges: let's look at what the browser will send to the server in this case, and let's see how the server responds: get /resources/public-data/ http/1.1 host: bar.other user-agent: mozilla/5.0 (macintosh; intel mac os x 10.14; rv:71.0) gecko/20100101 firefox/71.
... the following is an example of a request that will be preflighted: const xhr = new xmlhttprequest(); xhr.open('post', 'https://bar.other/resources/post-here/'); xhr.setrequestheader('x-pingother', 'pingpong'); xhr.setrequestheader('content-type', 'application/xml'); xhr.onreadystatechange = handler; xhr.send('<person><name>arun</name></person>'); the example above creates an xml body to send with the post request.
...content on foo.example might contain javascript like this: const invocation = new xmlhttprequest(); const url = 'http://bar.other/resources/credentialed-content/'; function callotherdomain() { if (invocation) { invocation.open('get', url, true); invocation.withcredentials = true; invocation.onreadystatechange = handler; invocation.send(); } } line 7 shows the flag on xmlhttprequest that has to be set in order to make the invocation with cookies, namely the withcredentials boolean value.

jspage - Archive of obsolete content
s:false,evalresponse:false,nocache:false},initialize:function(a){this.xhr=new browser.request(); this.setoptions(a);this.options.issuccess=this.options.issuccess||this.issuccess;this.headers=new hash(this.options.headers);},onstatechange:function(){if(this.xhr.readystate!=4||!this.running){return; }this.running=false;this.status=0;$try(function(){this.status=this.xhr.status;}.bind(this));this.xhr.onreadystatechange=$empty;if(this.options.issuccess.call(this,this.status)){this.response={text:this.xhr.responsetext,xml:this.xhr.responsexml}; this.success(this.response.text,this.response.xml);}else{this.response={text:null,xml:null};this.failure();}},issuccess:function(){return((this.status>=200)&&(this.status<300)); },processscripts:function(a){if(this.options.evalresponse||(/(ecma|java)script/).test(this.geth...
...tions.encoding)?"; charset="+this.options.encoding:""; this.headers.set("content-type","application/x-www-form-urlencoded"+c);}if(this.options.nocache){var f="nocache="+new date().gettime();g=(g)?f+"&"+g:f; }var e=b.lastindexof("/");if(e>-1&&(e=b.indexof("#"))>-1){b=b.substr(0,e);}if(g&&a=="get"){b=b+(b.contains("?")?"&":"?")+g;g=null;}this.xhr.open(a.touppercase(),b,this.options.async); this.xhr.onreadystatechange=this.onstatechange.bind(this);this.headers.each(function(m,l){try{this.xhr.setrequestheader(l,m);}catch(n){this.fireevent("exception",[l,m]); }},this);this.fireevent("request");this.xhr.send(g);if(!this.options.async){this.onstatechange();}return this;},cancel:function(){if(!this.running){return this; }this.running=false;this.xhr.abort();this.xhr.onreadystatechange=$empty;this.xhr=new browser.req...

Document - Web APIs
document.onreadystatechange represents the event handling code for the readystatechange event.
... also available via the onreadystatechange property.

EventTarget.addEventListener() - Web APIs
element; e.currenttarget=self; if (typeof listener.handleevent != 'undefined') { listener.handleevent(e); } else { listener.call(self,e); } }; if (type=="domcontentloaded") { var wrapper2=function(e) { if (document.readystate=="complete") { wrapper(e); } }; document.attachevent("onreadystatechange",wrapper2); eventlisteners.push({object:this,type:type,listener:listener,wrapper:wrapper2}); if (document.readystate=="complete") { var e=new event(); e.srcelement=window; wrapper2(e); } } else { this.attachevent("on"+type,wrapper); eventlisteners.push({object:this,type:type,listener:listener,wrapper:wrapper}); } ...
... }; var removeeventlistener=function(type,listener /*, usecapture (will be ignored) */) { var counter=0; while (counter<eventlisteners.length) { var eventlistener=eventlisteners[counter]; if (eventlistener.object==this && eventlistener.type==type && eventlistener.listener==listener) { if (type=="domcontentloaded") { this.detachevent("onreadystatechange",eventlistener.wrapper); } else { this.detachevent("on"+type,eventlistener.wrapper); } eventlisteners.splice(counter, 1); break; } ++counter; } }; element.prototype.addeventlistener=addeventlistener; element.prototype.removeeventlistener=removeeventlistener; if (htmldocument) { htmldocument.prototype.addeventl...

Index - Web APIs
5184 xmlhttprequest.onreadystatechange api, event, handler, property, reference, xhr, xmlhttprequest an eventhandler that is called whenever the readystate attribute changes.
...the xmlhttprequest.onreadystatechange property contains the event handler to be called when the readystatechange event is fired, that is every time the readystate property of the xmlhttprequest changes.

XMLHttpRequest.getAllResponseHeaders() - Web APIs
example this example examines the headers in the request's readystatechange event handler, xmlhttprequest.onreadystatechange.
... var request = new xmlhttprequest(); request.open("get", "foo.txt", true); request.send(); request.onreadystatechange = function() { if(this.readystate == this.headers_received) { // get the raw header string var headers = request.getallresponseheaders(); // convert the header string into an array // of individual headers var arr = headers.trim().split(/[\r\n]+/); // create a map of header names to values var headermap = {}; arr.foreach(function (line) { var parts = line.split(': '); var header = parts.shift(); var value = parts.join(': '); heade...

XMLHttpRequest - Web APIs
xmlhttprequest.onreadystatechange an eventhandler that is called whenever the readystate attribute changes.
... event handlers onreadystatechange as a property of the xmlhttprequest instance is supported in all browsers.

Communication between HTML and your extension - Archive of obsolete content
the onreadystatechange was set to another little javascript function that would update a specific element on the html page with the result.

Using SOAP in XULRunner 1.9 - Archive of obsolete content
req.setrequestheader("method", "post"); < req.setrequestheader("content-length", soapclient.contentlength); < req.setrequestheader("soapserver", soapclient.soapserver); < req.setrequestheader("soapaction", soapreq.action); < } < }); --- > var xhr = new xmlhttprequest(); > xhr.mozbackgroundrequest = true; > xhr.open('post', soapclient.proxy, true); > xhr.onreadystatechange = function() { > if (4 != xhr.readystate) { return; } > getresponse(xhr); > }; > var headers = { > 'method': 'post', > 'content-type': soapclient.contenttype + '; charset="' + > soapclient.charset + '"', > 'content-length': soapclient.contentlength, > 'soapserver': soapclient.soapserver, > 'soapaction': soapreq.action > }; > for (var h in headers) { xh...

nsIXMLHttpRequest
the 'onload', 'onerror', and 'onreadystatechange' attributes moved to nsijsxmlhttprequest, but if you're coding in c++ you should avoid using those.

Document.readyState - Web APIs
console.log("the first css rule is: " + document.stylesheets[0].cssrules[0].csstext); break; } readystatechange as an alternative to domcontentloaded event // alternative to domcontentloaded event document.onreadystatechange = function () { if (document.readystate === 'interactive') { initapplication(); } } readystatechange as an alternative to load event // alternative to load event document.onreadystatechange = function () { if (document.readystate === 'complete') { initapplication(); } } readystatechange as event listener to insert or modify the dom before domcontentloaded document.addeventlis...

Document: readystatechange event - Web APIs
bubbles no cancelable no interface event event handler property onreadystatechange examples live example html <div class="controls"> <button id="reload" type="button">reload</button> </div> <div class="event-log"> <label>event log:</label> <textarea readonly class="event-log-contents" rows="8" cols="30"></textarea> </div> css body { display: grid; grid-template-areas: "control log"; } .controls { grid-area: control; display: flex; align-items: center; justify-content: center; } .event-log { grid-area: log; } .event-log-contents { resize: none; } label, button { display: block; } #reload { height: 2rem; } js const log...

Using files from web applications - Web APIs
?><!doctype html> <html> <head> <title>dnd binary upload</title> <meta http-equiv="content-type" content="text/html; charset=utf-8"> <script type="application/javascript"> function sendfile(file) { const uri = "/index.php"; const xhr = new xmlhttprequest(); const fd = new formdata(); xhr.open("post", uri, true); xhr.onreadystatechange = function() { if (xhr.readystate == 4 && xhr.status == 200) { alert(xhr.responsetext); // handle response.