1 import { ObservableInput, OperatorFunction } from '../types';
2 import { switchMap } from './switchMap';
4 /* tslint:disable:max-line-length */
5 export function switchMapTo<R>(observable: ObservableInput<R>): OperatorFunction<any, R>;
6 /** @deprecated resultSelector is no longer supported. Switch to using switchMap with an inner map */
7 export function switchMapTo<T, R>(observable: ObservableInput<R>, resultSelector: undefined): OperatorFunction<T, R>;
8 /** @deprecated resultSelector is no longer supported. Switch to using switchMap with an inner map */
9 export function switchMapTo<T, I, R>(observable: ObservableInput<I>, resultSelector: (outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R): OperatorFunction<T, R>;
10 /* tslint:enable:max-line-length */
13 * Projects each source value to the same Observable which is flattened multiple
14 * times with {@link switchMap} in the output Observable.
16 * <span class="informal">It's like {@link switchMap}, but maps each value
17 * always to the same inner Observable.</span>
19 * ![](switchMapTo.png)
21 * Maps each source value to the given Observable `innerObservable` regardless
22 * of the source value, and then flattens those resulting Observables into one
23 * single Observable, which is the output Observable. The output Observables
24 * emits values only from the most recently emitted instance of
28 * Rerun an interval Observable on every click event
30 * import { fromEvent, interval } from 'rxjs';
31 * import { switchMapTo } from 'rxjs/operators';
33 * const clicks = fromEvent(document, 'click');
34 * const result = clicks.pipe(switchMapTo(interval(1000)));
35 * result.subscribe(x => console.log(x));
38 * @see {@link concatMapTo}
39 * @see {@link switchAll}
40 * @see {@link switchMap}
41 * @see {@link mergeMapTo}
43 * @param {ObservableInput} innerObservable An Observable to replace each value from
44 * the source Observable.
45 * @return {Observable} An Observable that emits items from the given
46 * `innerObservable` (and optionally transformed through the deprecated `resultSelector`)
47 * every time a value is emitted on the source Observable, and taking only the values
48 * from the most recently projected inner Observable.
52 export function switchMapTo<T, I, R>(
53 innerObservable: ObservableInput<I>,
54 resultSelector?: (outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R
55 ): OperatorFunction<T, I|R> {
56 return resultSelector ? switchMap(() => innerObservable, resultSelector) : switchMap(() => innerObservable);