switchMap 3

RxJS 5 switchMap

by Brian Troncone

HTML

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

JavaScript

//emit immediately, then every 5s
const source = Rx.Observable.timer(0, 5000);
//switch to new inner observable when source emits, invoke project function and emit values
const example = source.switchMap(() => Rx.Observable.interval(2000), (outerValue, innerValue, outerIndex, innerIndex) => ({outerValue, innerValue, outerIndex, innerIndex}));
/*
	Output:
	{outerValue: 0, innerValue: 0, outerIndex: 0, innerIndex: 0}
	{outerValue: 0, innerValue: 1, outerIndex: 0, innerIndex: 1}
	{outerValue: 1, innerValue: 0, outerIndex: 1, innerIndex: 0}
	{outerValue: 1, innerValue: 1, outerIndex: 1, innerIndex: 1}
*/
const subscribe = example.subscribe(val => console.log(val));