58 lines
2.6 KiB
Plaintext
58 lines
2.6 KiB
Plaintext
import { ObservableInput, OperatorFunction } from '../types';
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import { switchMap } from './switchMap';
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/* tslint:disable:max-line-length */
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export function switchMapTo<R>(observable: ObservableInput<R>): OperatorFunction<any, R>;
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/** @deprecated resultSelector is no longer supported. Switch to using switchMap with an inner map */
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export function switchMapTo<T, R>(observable: ObservableInput<R>, resultSelector: undefined): OperatorFunction<T, R>;
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/** @deprecated resultSelector is no longer supported. Switch to using switchMap with an inner map */
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export function switchMapTo<T, I, R>(observable: ObservableInput<I>, resultSelector: (outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R): OperatorFunction<T, R>;
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/* tslint:enable:max-line-length */
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/**
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* Projects each source value to the same Observable which is flattened multiple
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* times with {@link switchMap} in the output Observable.
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*
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* <span class="informal">It's like {@link switchMap}, but maps each value
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* always to the same inner Observable.</span>
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*
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* 
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*
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* Maps each source value to the given Observable `innerObservable` regardless
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* of the source value, and then flattens those resulting Observables into one
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* single Observable, which is the output Observable. The output Observables
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* emits values only from the most recently emitted instance of
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* `innerObservable`.
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*
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* ## Example
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* Rerun an interval Observable on every click event
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* ```ts
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* import { fromEvent, interval } from 'rxjs';
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* import { switchMapTo } from 'rxjs/operators';
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*
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* const clicks = fromEvent(document, 'click');
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* const result = clicks.pipe(switchMapTo(interval(1000)));
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* result.subscribe(x => console.log(x));
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* ```
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*
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* @see {@link concatMapTo}
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* @see {@link switchAll}
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* @see {@link switchMap}
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* @see {@link mergeMapTo}
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*
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* @param {ObservableInput} innerObservable An Observable to replace each value from
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* the source Observable.
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* @return {Observable} An Observable that emits items from the given
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* `innerObservable` (and optionally transformed through the deprecated `resultSelector`)
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* every time a value is emitted on the source Observable, and taking only the values
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* from the most recently projected inner Observable.
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* @method switchMapTo
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* @owner Observable
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*/
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export function switchMapTo<T, I, R>(
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innerObservable: ObservableInput<I>,
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resultSelector?: (outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R
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): OperatorFunction<T, I|R> {
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return resultSelector ? switchMap(() => innerObservable, resultSelector) : switchMap(() => innerObservable);
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}
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