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map
signature: map(project: Function, thisArg: any): Observable
Apply projection with each value from source.
New to transformation operators? Check out the article Get started transforming streams with map, pluck, and mapTo!
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Examples
Example 1: Add 10 to each number
( StackBlitz | jsBin | jsFiddle )
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// RxJS v6+
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import { from } from 'rxjs';
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import { map } from 'rxjs/operators';
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​
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//emit (1,2,3,4,5)
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const source = from([1, 2, 3, 4, 5]);
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//add 10 to each value
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const example = source.pipe(map(val => val + 10));
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//output: 11,12,13,14,15
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const subscribe = example.subscribe(val => console.log(val));
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Example 2: Map to single property
( StackBlitz | jsBin | jsFiddle )
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// RxJS v6+
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import { from } from 'rxjs';
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import { map } from 'rxjs/operators';
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​
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//emit ({name: 'Joe', age: 30}, {name: 'Frank', age: 20},{name: 'Ryan', age: 50})
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const source = from([
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  { name: 'Joe', age: 30 },
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  { name: 'Frank', age: 20 },
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  { name: 'Ryan', age: 50 }
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]);
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//grab each persons name, could also use pluck for this scenario
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const example = source.pipe(map(({ name }) => name));
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//output: "Joe","Frank","Ryan"
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const subscribe = example.subscribe(val => console.log(val));
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Additional Resources
​map 📰 - Official docs
​map - In Depth Dev Reference
​map vs flatMap 🎥 - Ben
Lesh
​Transformation operator: map and mapTo 🎥 💵 - André Staltz
​Build your own map operator 🎥 - Kwinten Pisman
📁 Source Code: https://github.com/ReactiveX/rxjs/blob/master/src/internal/operators/map.ts​
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Last modified 6mo ago
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Contents
Apply projection with each value from source.
Examples
Related Recipes
Additional Resources