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An EventHandler
that is called whenever the readyState
attribute changes. The callback is called from the user interface thread. 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. The callback is called from the user interface thread.
Warning: This should not be used with synchronous requests and must not be used from native code.
The readystatechange
event will not be fired when an XMLHttpRequest
request is canceled with the abort() method.
Syntax
XMLHttpRequest.onreadystatechange = callback;
Values
callback
is the function to be executed when thereadyState
changes.
Example
var xhr = new XMLHttpRequest(), method = "GET", url = "https://developer.mozilla.org/"; xhr.open(method, url, true); xhr.onreadystatechange = function () { if(xhr.readyState === XMLHttpRequest.DONE && xhr.status === 200) { console.log(xhr.responseText); } }; xhr.send();
Specifications
Specification | Status | Comment |
---|---|---|
XMLHttpRequest | Living Standard | WHATWG living standard |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 1 | 1.0 (1.7 or earlier) | 7[1] | (Yes) | 1.2 |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | ? | 1.0 | (Yes) | ? | ? | ? |
[1] Internet Explorer version 5 and 6 supported ajax calls using ActiveXObject()
.