bufferwhen.md

bufferWhen

signature: bufferWhen(closingSelector: function): Observable

Collect all values until closing selector emits, emit buffered values.

Examples

Example 1: Emit buffer based on interval

( StackBlitz | jsBin | jsFiddle )

// RxJS v6+
import { interval } from 'rxjs';
import { bufferWhen } from 'rxjs/operators';

//emit value every 1 second
const oneSecondInterval = interval(1000);
//return an observable that emits value every 5 seconds
const fiveSecondInterval = () => interval(5000);
//every five seconds, emit buffered values
const bufferWhenExample = oneSecondInterval.pipe(
  bufferWhen(fiveSecondInterval)
);
//log values
//ex. output: [0,1,2,3]...[4,5,6,7,8]
const subscribe = bufferWhenExample.subscribe(val =>
  console.log('Emitted Buffer: ', val)
);

Additional Resources

• bufferWhen 📰 - Official docs
• bufferWhen - In Depth Dev Reference

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📁 Source Code: https://github.com/ReactiveX/rxjs/blob/master/src/internal/operators/bufferWhen.ts