pcancel

Wrap promise function into cancelable promise function

Sometimes you may need to create cancelable promise for situation like to avoid isMounted antipattern in React. pcancel provides simple utility for creating cancelable promises. Highly inspired from this comment.

Install

$ npm install --save pcancel

Usage

import pcancel from 'pcancel';
 
const delayC = pcancel(delay);
const p = delayC(4000)
  .promise
  .then(() => console.log('Yey!'))
  .catch((err) => console.error(err));
 
p.cancel(); // Error: Promise has canceled
 
function delay(time) {
  return new Promise((resolve) => setTimeout(() => resolve(), time));
}

API

pcancel(fn[, options])

• fn Function - Promise-returning function that will be cancelable.
• options Object (optional)
  • noReject Boolean - Whether to reject when canceling. If this option is true, the promise will be resolved with the value passed through to cancel() method on the promise.

Returns a wrapped function that returns object includes Promise instance and cancel() function.

You can also specify error or value through cancel() method, the specified value will be returned instead of value of the promise:

p.cancel(new Error('Foo')); // Error: Foo

Note: cancel() rejects the promise immediately when it called.

License

MIT