Implement a Cancelable Promise (with CancelToken / AbortController)

Question

Accepted Answer

**Approach:** Wrap promise with controller that rejects on cancel signal. Use `AbortController` for standard.

```javascript
class CancelError extends Error { constructor(msg='Cancelled'){ super(msg); this.name='CancelError'; } }
function makeCancelable(promise) {
  let canceled = false, cancel;
  const cancelPromise = new Promise((_, reject) => { cancel = () => { canceled = true; reject(new CancelError()); }; });
  const wrapped = Promise.race([promise, cancelPromise]);
  promise.catch(()=>{});
  return { promise: wrapped, cancel, isCanceled: () => canceled };
}
function withAbort(promise, signal) {
  if (signal.aborted) return Promise.reject(new DOMException('Aborted','AbortError'));
  return new Promise((resolve, reject) => {
    const onAbort = () => reject(new DOMException('Aborted','AbortError'));
    signal.addEventListener('abort', onAbort, { once: true });
    promise.then(v => { signal.removeEventListener('abort', onAbort); resolve(v); }, e => { signal.removeEventListener('ab

Implement a Cancelable Promise (with CancelToken / AbortController)

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Understand the problem

Attempt it yourself

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Solution ready — 2 min read

Join the discussion

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KEEP THESTREAK ALIVE.

KEEP THE
STREAK ALIVE.