> For the complete documentation index, see [llms.txt](https://chasethestar.gitbook.io/ko.learn-rxjs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://chasethestar.gitbook.io/ko.learn-rxjs/rxjs/operators/transformation/buffer.md).

# buffer

#### signature: `buffer(closingNotifier: Observable): Observable`

## Collect output values until provided observable emits, emit as array.

[![Ultimate RxJS](https://drive.google.com/uc?export=view\&id=1qq2-q-eVe-F_-d0eSvTyqaGRjpfLDdJz)](https://ultimatecourses.com/courses/rxjs?ref=4)

### Examples

**Example 1: Using buffer to recognize double clicks**

( [StackBlitz](https://stackblitz.com/edit/typescript-x5zyn5?file=index.ts\&devtoolsheight=50))

```js
// RxJS v6+
import { fromEvent } from 'rxjs';
import { buffer, filter, throttleTime } from 'rxjs/operators';

// streams
const clicks$ = fromEvent(document, 'click');

/*
Collect clicks that occur, after 250ms emit array of clicks
*/
clicks$
  .pipe(
    buffer(clicks$.pipe(throttleTime(250))),
    // if array is greater than 1, double click occured
    filter(clickArray => clickArray.length > 1)
  )
  .subscribe(() => console.log('Double Click!'));
```

**Example 2: Buffer until document click**

( [StackBlitz](https://stackblitz.com/edit/typescript-nwp2cl?file=index.ts\&devtoolsheight=50) | [jsBin](http://jsbin.com/fazimarajo/edit?js,console,output) | [jsFiddle](https://jsfiddle.net/btroncone/7451s67k/) )

```js
// RxJS v6+
import { interval, fromEvent } from 'rxjs';
import { buffer } from 'rxjs/operators';

//Create an observable that emits a value every second
const myInterval = interval(1000);
//Create an observable that emits every time document is clicked
const bufferBy = fromEvent(document, 'click');
/*
Collect all values emitted by our interval observable until we click document. This will cause the bufferBy Observable to emit a value, satisfying the buffer. Pass us all collected values since last buffer as an array.
*/
const myBufferedInterval = myInterval.pipe(buffer(bufferBy));
//Print values to console
//ex. output: [1,2,3] ... [4,5,6,7,8]
const subscribe = myBufferedInterval.subscribe(val =>
  console.log(' Buffered Values:', val)
);
```

### Related Recipes

* [Game Loop](/ko.learn-rxjs/rxjs/recipes/gameloop.md)

### Additional Resources

* [buffer](https://rxjs-dev.firebaseapp.com/api/operators/buffer) 📰 - Official docs
* [buffer](https://indepth.dev/reference/rxjs/operators/buffer) - In Depth Dev Reference
* [Transformation operator: buffer](https://egghead.io/lessons/rxjs-transformation-operator-buffer?course=rxjs-beyond-the-basics-operators-in-depth) 🎥 💵 - André Staltz

***

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