AbortController: signal property - Web APIs | MDN (original) (raw)

Baseline

Widely available

Note: This feature is available in Web Workers.

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

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 (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.

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

const url = "video.mp4";
const downloadBtn = document.querySelector(".download");
const abortBtn = document.querySelector(".abort");

downloadBtn.addEventListener("click", fetchVideo);

abortBtn.addEventListener("click", () => {
  controller.abort();
  console.log("Download aborted");
});

function fetchVideo() {
  fetch(url, { signal })
    .then((response) => {
      console.log("Download complete", response);
    })
    .catch((err) => {
      console.error(`Download error: ${err.message}`);
    });
}

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

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

Specifications

Browser compatibility

See also