# 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](https://stackblitz.com/edit/typescript-f4a2fu?file=index.ts\&devtoolsheight=10) | [jsBin](http://jsbin.com/vugerupube/1/edit?js,console) | [jsFiddle](https://jsfiddle.net/btroncone/nr9agfuL/) )

```js
// 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](https://rxjs.dev/api/operators/bufferWhen) 📰 - Official docs

***

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


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