work.suroh.tk/node_modules/rxjs/_esm2015/operator/exhaustMap.js

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2.5 KiB
JavaScript

import { exhaustMap as higherOrder } from '../operators/exhaustMap';
/* tslint:enable:max-line-length */
/**
* Projects each source value to an Observable which is merged in the output
* Observable only if the previous projected Observable has completed.
*
* <span class="informal">Maps each value to an Observable, then flattens all of
* these inner Observables using {@link exhaust}.</span>
*
* <img src="./img/exhaustMap.png" width="100%">
*
* Returns an Observable that emits items based on applying a function that you
* supply to each item emitted by the source Observable, where that function
* returns an (so-called "inner") Observable. When it projects a source value to
* an Observable, the output Observable begins emitting the items emitted by
* that projected Observable. However, `exhaustMap` ignores every new projected
* Observable if the previous projected Observable has not yet completed. Once
* that one completes, it will accept and flatten the next projected Observable
* and repeat this process.
*
* @example <caption>Run a finite timer for each click, only if there is no currently active timer</caption>
* var clicks = Rx.Observable.fromEvent(document, 'click');
* var result = clicks.exhaustMap((ev) => Rx.Observable.interval(1000).take(5));
* result.subscribe(x => console.log(x));
*
* @see {@link concatMap}
* @see {@link exhaust}
* @see {@link mergeMap}
* @see {@link switchMap}
*
* @param {function(value: T, ?index: number): ObservableInput} project A function
* that, when applied to an item emitted by the source Observable, returns an
* Observable.
* @param {function(outerValue: T, innerValue: I, outerIndex: number, innerIndex: number): any} [resultSelector]
* A function to produce the value on the output Observable based on the values
* and the indices of the source (outer) emission and the inner Observable
* emission. The arguments passed to this function are:
* - `outerValue`: the value that came from the source
* - `innerValue`: the value that came from the projected Observable
* - `outerIndex`: the "index" of the value that came from the source
* - `innerIndex`: the "index" of the value from the projected Observable
* @return {Observable} An Observable containing projected Observables
* of each item of the source, ignoring projected Observables that start before
* their preceding Observable has completed.
* @method exhaustMap
* @owner Observable
*/
export function exhaustMap(project, resultSelector) {
return higherOrder(project, resultSelector)(this);
}
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