/
pluck.ts
33 lines (32 loc) · 1.25 KB
/
pluck.ts
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
import { Observable } from 'rxjs';
import { pluck as higherOrder } from 'rxjs/operators';
/**
* Maps each source value (an object) to its specified nested property.
*
* <span class="informal">Like {@link map}, but meant only for picking one of
* the nested properties of every emitted object.</span>
*
* <img src="./img/pluck.png" width="100%">
*
* Given a list of strings describing a path to an object property, retrieves
* the value of a specified nested property from all values in the source
* Observable. If a property can't be resolved, it will return `undefined` for
* that value.
*
* @example <caption>Map every click to the tagName of the clicked target element</caption>
* var clicks = Rx.Observable.fromEvent(document, 'click');
* var tagNames = clicks.pluck('target', 'tagName');
* tagNames.subscribe(x => console.log(x));
*
* @see {@link map}
*
* @param {...string} properties The nested properties to pluck from each source
* value (an object).
* @return {Observable} A new Observable of property values from the source values.
* @method pluck
* @owner Observable
*/
export function pluck<T, R>(this: Observable<T>, ...properties: string[]): Observable<R> {
// @ts-ignore
return higherOrder(...properties)(this) as Observable<R>;
}