forkJoin

RxJS 5 forkJoin

by John Grden

HTML

<script src="https://npmcdn.com/@reactivex/[email protected]/dist/global/Rx.umd.js"></script>

JavaScript

const myPromise = val => new Promise(resolve => setTimeout(() => resolve(`Promise Resolved: ${val}`), 5000))

const obs_test = Rx.Observable.create(subscriber => {
	subscriber.next('message from obs_test');
});

const obs_0 = Rx.Observable.create(subscriber => {
  obs_test.subscribe(
  		data => {
      	subscriber.next(data);
        subscriber.complete();
      }
    );
});

/*
  when all observables complete, give the last
  emitted value from each as an array
*/
const example = Rx.Observable.forkJoin(
  //emit 'Hello' immediately
  Rx.Observable.of('Hello'),
  //emit 'World' after 1 second
  Rx.Observable.of('World').delay(1000),
  //emit 0 after 1 second
  Rx.Observable.interval(1000).take(1),
  //emit 0...1 in 1 second interval
  Rx.Observable.interval(1000).take(2),
  //promise that resolves to 'Promise Resolved' after 5 seconds
  myPromise('RESULT'),
  // nested observables
  obs_0
);
//output: ["Hello", "World", 0, 1, "Promise Resolved: RESULT"]
const subscribe = example.subscribe(val => console.log(val));