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

# race

#### signature: `race(): Observable`

## The observable to emit first is used.

### Why use race?

The `race` operator is the go-to choice when you want to work with multiple observables that compete against each other, and you're only interested in the first one to emit a value. It's like a competitive race, where the first runner to cross the finish line claims the victory, and the others don't matter anymore (if you're not first you're last?).

A relatable example of using `race` can be observed in an image loading scenario. Imagine you have two sources to load an image from, and you want to display the image as soon as possible. You can use the race operator to subscribe to both sources, and once the first source successfully loads the image, it will emit the value, and the subscription to the other source will be automatically unsubscribed.

It's crucial to remember that `race` only pays attention to the first emitted value from the competing observables. Once an observable wins the race, the other observables are disregarded, and their potential future emissions will have no impact on the output.

If your use case involves working with multiple observables that should all emit values and complete, or you need to process the emitted values in a specific order, consider using operators like [combineLatest](/learn-rxjs/operators/combination/combinelatest.md) or [forkJoin](/learn-rxjs/operators/combination/forkjoin.md) instead.

### Examples

**Example 1: race with 4 observables**

( [StackBlitz](https://stackblitz.com/edit/typescript-cvfmug?file=index.ts\&devtoolsheight=100) | [jsBin](http://jsbin.com/goqiwobeno/1/edit?js,console) | [jsFiddle](https://jsfiddle.net/btroncone/8jcmb1ec/) )

```js
// RxJS v6+
import { mapTo } from 'rxjs/operators';
import { interval } from 'rxjs/observable/interval';
import { race } from 'rxjs/observable/race';

//take the first observable to emit
const example = race(
  //emit every 1.5s
  interval(1500),
  //emit every 1s
  interval(1000).pipe(mapTo('1s won!')),
  //emit every 2s
  interval(2000),
  //emit every 2.5s
  interval(2500)
);
//output: "1s won!"..."1s won!"...etc
const subscribe = example.subscribe(val => console.log(val));
```

**Example 2: race with an error**

( [StackBlitz](https://stackblitz.com/edit/typescript-in6fw6?file=index.ts\&devtoolsheight=100) | [jsFiddle](https://jsfiddle.net/gbeL4t55/2/) )

```js
// RxJS v6+
import { delay, map } from 'rxjs/operators';
import { of, race } from 'rxjs';

//Throws an error and ignores the other observables.
const first = of('first').pipe(
  delay(100),
  map(_ => {
    throw 'error';
  })
);
const second = of('second').pipe(delay(200));
const third = of('third').pipe(delay(300));
// nothing logged
race(first, second, third).subscribe(val => console.log(val));
```

### Additional Resources

* [race](http://reactivex.io/rxjs/class/es6/Observable.js~Observable.html#instance-method-race) 📰 - Official docs

***

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


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## 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, and the optional `goal` query parameter:

```
GET https://www.learnrxjs.io/learn-rxjs/operators/combination/race.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

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.