Canceling asynchronous actions with Promise.race()

ES6 introduces Promise.race(), which is absent from the $q spec in Angular 1. Like Promise.all(), this static method accepts an iterable collection of promise objects; whichever one resolves or rejects first will become the result of the promise wrapping the collection. This may seem like unusual behavior, but it becomes quite useful when you're building a cancellation behavior into the system.

Note

The code, links, and a live example of this are available at http://ngcookbook.herokuapp.com/4362/ .

Getting ready

Suppose you started with a simple promise that resolves to a value after 3 seconds:

const delayedPromise = new Promise((resolve, reject) =>  
  setTimeout(resolve.bind(null, 'foobar'), 3000)) 
.then(val => console.log(val)); 

You would like to have the ability to detach a part of your application from waiting for this promise.

How to do it...

A simple solution would be to expose the promise's reject handler and just...