AbortSignal

The AbortSignal interface represents a signal object that allows you to communicate with a DOM request (such as a fetch request) and abort it if required via an AbortController object.

The AbortSignal interface also inherits properties from its parent interface, EventTarget.

AbortSignal.aborted Read only

A Boolean that indicates whether the request(s) the signal is communicating with is/are aborted (true) or not (false).

AbortSignal.reason Read only

A JavaScript value providing the abort reason, once the signal has aborted.

Listen to this event using addEventListener() or by assigning an event listener to the oneventname property of this interface.

abort

Invoked when the DOM requests the signal is communicating with is/are aborted. Also available via the onabort property.

The AbortSignal interface inherits methods from its parent interface, EventTarget.

AbortSignal.throwIfAborted()

Throws the signal's abort reason if the signal has been aborted; otherwise it does nothing.

AbortSignal.abort()

Returns an AbortSignal instance that is already set as aborted.

The following snippet shows how we might use a signal to abort downloading a video using the Fetch API.

We first create an abort 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 (the {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;
  })
}

You can find a full working example on GitHub; you can also see it running live.

• Fetch API
• Abortable Fetch by Jake Archibald