This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.
The onabort read-only property of the FetchSignal interface is an event handler Invoked when an abort event fires, i.e. when the fetch request(s) the signal is communicating with is/are aborted.
Syntax
signal.onabort = function() { ... };
Examples
In the following snippet, we create a new FetchController object, get its signal, and then give the signal to the fetch request via the signal parameter of its init object so the controller can control it. Later on we specify an event listener on the FetchSignal so that when if is aborted, a log is sent to the console.
var controller = new FetchController();
var signal = controller.signal;
signal.onabort = function() {
console.log('Fetch request cancelled');
};
You can find a work-in-progress demo showing usage of FetchController on GitHub (see the source code and the live example).
Specifications
Not part of a specification yet.
Browser compatibility
| Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
|---|---|---|---|---|---|---|
| Basic support |
No support |
No support | No support[1] | No support |
No support |
No support |
| Feature | Android | Android Webview | Edge | Firefox Mobile (Gecko) | IE Phone | Opera Mobile | Safari Mobile | Chrome for Android |
|---|---|---|---|---|---|---|---|---|
| Basic support | No support | No support | No support | No support[1] | No support | No support | No support | No support |
[1] Hidden behind a preference in 55+ Nightly. In about:config, you need to create two new boolean prefs — dom.fetchObserver.enabled and dom.fetchController.enabled — and set the values of both to true.