Web/API/AbortController/signal

The signal read-only property of the AbortController interface returns an AbortSignal object instance, which can be used to communicate with/abort a DOM request as desired.

Syntax

var signal = abortController.signal;

Value

An AbortSignal object instance.

Examples

In the following snippet, we aim to download a video using the Fetch API.

We first create a controller using the AbortController() constructor, then grab a reference to its associated AbortSignal object using the AbortController.signal property.

When the fetch request is initiated, we pass in the AbortSignal as an option inside the request's options object (see {signal}, below). This associates the signal and controller with the fetch request and allows us to abort it by calling AbortController.abort(), as seen below in the second event listener.

var controller = new AbortController();
var signal = controller.signal;

var downloadBtn = document.querySelector('.download');
var abortBtn = document.querySelector('.abort');

downloadBtn.addEventListener('click', fetchVideo);

abortBtn.addEventListener('click', function() {
  controller.abort();
  console.log('Download aborted');
});

function fetchVideo() {
  ...
  fetch(url, {signal}).then(function(response) {
    ...
  }).catch(function(e) {
    reports.textContent = 'Download error: ' + e.message;
  })
}

Note: When abort() is called, the fetch() promise rejects with an AbortError.

You can find a full working example on GitHub — see abort-api ([[../../../../../../../mdn.github.io/dom-examples/abort-api/index|see it running live also]]).

Specifications

Specification	Status	Comment
DOMThe definition of 'signal' in that specification.	Living Standard	Initial definition

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`signal` Experimental'	Chrome Full support 66	Edge Full support 16	Firefox Full support 57	IE No support No	Opera Full support 53	Safari Full support 12.1 Full support 12.1 Partial support 11.1 Notes' Notes' Even though `window.AbortController` is defined, it doesn't really abort `fetch` requests. See bug 174980.	WebView Android Full support 66	Chrome Android Full support 66	Firefox Android Full support 57	Opera Android Full support 47	Safari iOS Full support 12.2 Full support 12.2 Partial support 11.3 Notes' Notes' Even though `window.AbortController` is defined, it doesn't really abort `fetch` requests. See bug 174980.	Samsung Internet Android Full support 9.0

Legend

Full support: Full support
No support: No support
Experimental. Expect behavior to change in the future.': Experimental. Expect behavior to change in the future.
See implementation notes.': See implementation notes.