How to cancel a promise with JavaScript?

To cancel a promise with JavaScript, we use the AbortController constructor.

For instance, we write

const controller = new AbortController();

const task = new Promise((resolve, reject) => {
  //...
  controller.signal.addEventListener("abort", () => {
    reject();
  });
});

controller.abort();

to create an AbortController object.

Then we create the promise with the Promise constructor called with a callback.

In it, we listen to the abort controller’s abort event by calling controller.signal.addEventListener in the task promise.

We call it with a callback that calls reject to reject the promise, which stops the promise from running.

Then we call controller.abort to cancel the promise, which triggers the abort event on the controller.