share

RxJS 5 share

by Brian Troncone

HTML

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

JavaScript

//emit value in 1s
const source = Rx.Observable.timer(1000);
//log side effect, emit result
const example = source
  .do(() => console.log('***SIDE EFFECT***'))
  .mapTo('***RESULT***');
/*
  ***NOT SHARED, SIDE EFFECT WILL BE EXECUTED TWICE***
  output: 
  "***SIDE EFFECT***"
  "***RESULT***"
  "***SIDE EFFECT***"
  "***RESULT***"
*/
const subscribe = example.subscribe(val => console.log(val));
const subscribeTwo = example.subscribe(val => console.log(val));

//share observable among subscribers
const sharedExample = example.share();
/*
  ***SHARED, SIDE EFFECT EXECUTED ONCE***
  output: 
  "***SIDE EFFECT***"
  "***RESULT***"
  "***RESULT***"
*/
const subscribeThree = sharedExample.subscribe(val => console.log(val));
const subscribeFour = sharedExample.subscribe(val => console.log(val));