# merge

#### signature: `merge(input: Observable): Observable`

## Turn multiple observables into a single observable.

:bulb: This operator can be used as either a static or instance method!

:bulb: If order not throughput is a primary concern, try [concat](https://junwoo45.gitbook.io/learn-rxjs-korean/learn-rxjs/recipes-1/combination/concat) instead!

### Examples

**Example 1: merging multiple observables, static method**

( [StackBlitz](https://stackblitz.com/edit/typescript-ohq6rx?file=index.ts\&devtoolsheight=100) | [jsBin](http://jsbin.com/conufujapi/1/edit?js,console) | [jsFiddle](https://jsfiddle.net/btroncone/qvq9dscu/) )

```javascript
// RxJS v6+
import { mapTo } from 'rxjs/operators';
import { interval, merge } from 'rxjs';

//emit every 2.5 seconds
const first = interval(2500);
//emit every 2 seconds
const second = interval(2000);
//emit every 1.5 seconds
const third = interval(1500);
//emit every 1 second
const fourth = interval(1000);

//emit outputs from one observable
const example = merge(
  first.pipe(mapTo('FIRST!')),
  second.pipe(mapTo('SECOND!')),
  third.pipe(mapTo('THIRD')),
  fourth.pipe(mapTo('FOURTH'))
);
//output: "FOURTH", "THIRD", "SECOND!", "FOURTH", "FIRST!", "THIRD", "FOURTH"
const subscribe = example.subscribe(val => console.log(val));
```

**Example 2: merge 2 observables, instance method**

( [StackBlitz](https://stackblitz.com/edit/typescript-bcsl1r?file=index.ts\&devtoolsheight=100) | [jsBin](http://jsbin.com/wuwujokaqu/1/edit?js,console) | [jsFiddle](https://jsfiddle.net/btroncone/me5ofcr0/) )

```javascript
// RxJS v6+
import { merge } from 'rxjs/operators';
import { interval } from 'rxjs';

//emit every 2.5 seconds
const first = interval(2500);
//emit every 1 second
const second = interval(1000);
//used as instance method
const example = first.pipe(merge(second));
//output: 0,1,0,2....
const subscribe = example.subscribe(val => console.log(val));
```

### Related Recipes

* [Battleship Game](https://junwoo45.gitbook.io/learn-rxjs-korean/learn-rxjs/recipes/battleship-game)
* [Flappy Bird Game](https://junwoo45.gitbook.io/learn-rxjs-korean/learn-rxjs/recipes/flappy-bird-game)
* [HTTP Polling](https://junwoo45.gitbook.io/learn-rxjs-korean/learn-rxjs/recipes/http-polling)
* [Lockscreen](https://junwoo45.gitbook.io/learn-rxjs-korean/learn-rxjs/recipes/lockscreen)
* [Memory Game](https://junwoo45.gitbook.io/learn-rxjs-korean/learn-rxjs/recipes/memory-game)
* \[Save Indicator]\('../../recipes/save-indicator.md)

### Additional Resources

* [merge](https://rxjs.dev/api/index/function/merge)

  :newspaper: - Official docs
* [Handling multiple streams with merge](https://egghead.io/lessons/rxjs-handling-multiple-streams-with-merge?course=step-by-step-async-javascript-with-rxjs)

  :video\_camera: :dollar: - John Linquist
* [Sharing network requests with merge](https://egghead.io/lessons/rxjs-reactive-programming-sharing-network-requests-with-rxjs-merge?course=introduction-to-reactive-programming)

  :video\_camera: :dollar: - André Staltz
* [Combination operator: merge](https://egghead.io/lessons/rxjs-combination-operator-merge?course=rxjs-beyond-the-basics-operators-in-depth)

  :video\_camera: :dollar: - André Staltz
* [Build your own merge operator](https://blog.strongbrew.io/build-the-operators-from-rxjs-from-scratch/?lectureId=merge#app)

  :video\_camera: - Kwinten Pisman

> :file\_folder: Source Code: <https://github.com/ReactiveX/rxjs/blob/master/src/internal/operators/merge.ts>


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://junwoo45.gitbook.io/learn-rxjs-korean/learn-rxjs/recipes-1/combination/merge.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.