# from

\`\`# from

**signature: `from(ish: ObservableInput, mapFn: function, thisArg: any, scheduler: Scheduler): Observable`**

### Turn an array, promise, or iterable into an observable.

***

💡 This operator can be used to convert a promise to an observable!

💡 For arrays and iterables, all contained values will be emitted as a sequence!

💡 This operator can also be used to emit a string as a sequence of characters!

***

#### Examples

**Example 1: Observable from array**

( [StackBlitz](https://stackblitz.com/edit/typescript-sckwsw?file=index.ts\&devtoolsheight=100) | [jsBin](http://jsbin.com/foceyuketi/1/edit?js,console) | [jsFiddle](https://jsfiddle.net/btroncone/o7kb5e6j/) )

```js
// RxJS v6+
import { from } from 'rxjs';

//emit array as a sequence of values
const arraySource = from([1, 2, 3, 4, 5]);
//output: 1,2,3,4,5
const subscribe = arraySource.subscribe(val => console.log(val));
```

**Example 2: Observable from promise**

( [StackBlitz](https://stackblitz.com/edit/typescript-clpg1f?file=index.ts\&devtoolsheight=100) | [jsBin](http://jsbin.com/tamofinujo/1/edit?js,console) | [jsFiddle](https://jsfiddle.net/btroncone/2czc5sae/) )

```js
// RxJS v6+
import { from } from 'rxjs';

//emit result of promise
const promiseSource = from(new Promise(resolve => resolve('Hello World!')));
//output: 'Hello World'
const subscribe = promiseSource.subscribe(val => console.log(val));
```

**Example 3: Observable from collection**

( [StackBlitz](https://stackblitz.com/edit/typescript-drfckx?file=index.ts\&devtoolsheight=100) | [jsBin](http://jsbin.com/tezohobudu/1/edit?js,console) | [jsFiddle](https://jsfiddle.net/btroncone/ae6hu9a8/) )

```js
// RxJS v6+
import { from } from 'rxjs';

//works on js collections
const map = new Map();
map.set(1, 'Hi');
map.set(2, 'Bye');

const mapSource = from(map);
//output: [1, 'Hi'], [2, 'Bye']
const subscribe = mapSource.subscribe(val => console.log(val));
```

**Example 4: Observable from string**

( [StackBlitz](https://stackblitz.com/edit/typescript-19nejh?file=index.ts\&devtoolsheight=100) | [jsBin](http://jsbin.com/wenozubana/1/edit?js,console) | [jsFiddle](https://jsfiddle.net/btroncone/hfvzjcvL/) )

```js
// RxJS v6+
import { from } from 'rxjs';

//emit string as a sequence
const source = from('Hello World');
//output: 'H','e','l','l','o',' ','W','o','r','l','d'
const subscribe = source.subscribe(val => console.log(val));
```

#### Related Recipes

* [HTTP Polling](https://www.learnrxjs.io/learn-rxjs/recipes/http-polling)
* [Lockscreen](https://www.learnrxjs.io/learn-rxjs/recipes/lockscreen)
* [Memory Game](https://www.learnrxjs.io/learn-rxjs/recipes/memory-game)
* [Progress Bar](https://www.learnrxjs.io/learn-rxjs/recipes/progressbar)

#### Additional Resources

* [from](https://rxjs.dev/api/index/function/from) 📰 - Official docs
* [Creation operators: from, fromArray, fromPromise](https://egghead.io/lessons/rxjs-creation-operators-from-fromarray-frompromise?course=rxjs-beyond-the-basics-creating-observables-from-scratch) 🎥 💵 - André Staltz

***

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