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  • Apply projection with each value from source.
  • Examples
  • Related Recipes
  • Additional Resources
  1. Learn RxJS
  2. Operators
  3. Transformation

map

PreviousgroupByNextmapTo

Last updated 1 year ago

signature: map(project: Function, thisArg: any): Observable

Apply projection with each value from source.

New to transformation operators? Check out the article !

Examples

Example 1: Add 10 to each number

( | | )

// RxJS v6+
import { from } from 'rxjs';
import { map } from 'rxjs/operators';

//emit (1,2,3,4,5)
const source = from([1, 2, 3, 4, 5]);
//add 10 to each value
const example = source.pipe(map(val => val + 10));
//output: 11,12,13,14,15
const subscribe = example.subscribe(val => console.log(val));

Example 2: Map to single property

// RxJS v6+
import { from } from 'rxjs';
import { map } from 'rxjs/operators';

//emit ({name: 'Joe', age: 30}, {name: 'Frank', age: 20},{name: 'Ryan', age: 50})
const source = from([
  { name: 'Joe', age: 30 },
  { name: 'Frank', age: 20 },
  { name: 'Ryan', age: 50 }
]);
//grab each persons name, could also use pluck for this scenario
const example = source.pipe(map(({ name }) => name));
//output: "Joe","Frank","Ryan"
const subscribe = example.subscribe(val => console.log(val));

Related Recipes

Additional Resources


( | | )

📰 - Official docs

- In Depth Dev Reference

🎥 - Ben Lesh

🎥 💵 - André Staltz

🎥 - Kwinten Pisman

📁 Source Code:

StackBlitz
jsBin
jsFiddle
Alphabet Invasion Game
Battleship Game
Catch The Dot Game
Game Loop
HTTP Polling
Lockscreen
Memory Game
Mine Sweeper Game
Save Indicator
Smart Counter
Space Invaders Game
Stop Watch
Swipe To Refresh
Tetris Game
Type Ahead
map
map
map vs flatMap
Transformation operator: map and mapTo
Build your own map operator
https://github.com/ReactiveX/rxjs/blob/master/src/internal/operators/map.ts
Get started transforming streams with map, pluck, and mapTo
StackBlitz
jsBin
jsFiddle