CancelToken and Cancel Polyfill

This a polyfill of the polyfillable parts of the proposed cancellable promises spec.

See https://github.com/littledan/proposal-cancelable-promises for more details.

Use

import {CancelToken} from 'cancel-token';

const source = CancelToken.source();

const result = someCancellableApi(source.token);

eventSource.on('dont-care-about-result-anymore', () {
  source.cancel();
});

// This may throw a Cancel if we called source.cancel().
const value = await result;


// Elsewhere, maybe in another library
async function someCancellableApi(cancelToken) {
  await doSomeWork(cancelToken);

  // I'm outside of a critical section here, so it's ok if I were to throw.
  cancelToken.throwIfRequested();

  return doSomeMoreWork(cancelToken);
}

Developing

To test:

npm test

To watch source files and rerun tests when they change:

npm test:watch

Change Log

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog and this project adheres to Semantic Versioning.

Unreleased

[0.1.1] - 2016-12-16

• Fixes an npm publish blunder.
• Adds basic README.md and CHANGELOG.md

[0.1.0] - 2016-12-16

• Initial release, with CancelToken and Cancel from the November 23rd, 2016 draft of https://tc39.github.io/proposal-cancelable-promises/ (now withdrawn).
• Looks like https://github.com/littledan/proposal-cancelable-promises may be picking up the spec and removing the syntactic parts, leaving just the polyfillable pieces implemented here.
• Also includes two non-spec'd but useful methods: isCancelToken and isCancel.