share

연산자(operator) 정의: share(): Observable

Share source among multiple subscribers.

share is like multicast with a Subject and refCount!

Examples

Example 1: Multiple subscribers sharing source

( jsBin | jsFiddle )

//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));

Additional Resources

• share - Official docs
• Sharing streams with share - John Linquist

Source Code: https://github.com/ReactiveX/rxjs/blob/master/src/operator/share.ts