work.suroh.tk/node_modules/rxjs/_esm5/operator/switchMapTo.js

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2019-12-02 12:22:45 +00:00
/** PURE_IMPORTS_START .._operators_switchMapTo PURE_IMPORTS_END */
import { switchMapTo as higherOrder } from '../operators/switchMapTo';
/* tslint:enable:max-line-length */
/**
* Projects each source value to the same Observable which is flattened multiple
* times with {@link switch} in the output Observable.
*
* <span class="informal">It's like {@link switchMap}, but maps each value
* always to the same inner Observable.</span>
*
* <img src="./img/switchMapTo.png" width="100%">
*
* Maps each source value to the given Observable `innerObservable` regardless
* of the source value, and then flattens those resulting Observables into one
* single Observable, which is the output Observable. The output Observables
* emits values only from the most recently emitted instance of
* `innerObservable`.
*
* @example <caption>Rerun an interval Observable on every click event</caption>
* var clicks = Rx.Observable.fromEvent(document, 'click');
* var result = clicks.switchMapTo(Rx.Observable.interval(1000));
* result.subscribe(x => console.log(x));
*
* @see {@link concatMapTo}
* @see {@link switch}
* @see {@link switchMap}
* @see {@link mergeMapTo}
*
* @param {ObservableInput} innerObservable An Observable to replace each value from
* the source 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 that emits items from the given
* `innerObservable` (and optionally transformed through `resultSelector`) every
* time a value is emitted on the source Observable, and taking only the values
* from the most recently projected inner Observable.
* @method switchMapTo
* @owner Observable
*/
export function switchMapTo(innerObservable, resultSelector) {
return higherOrder(innerObservable, resultSelector)(this);
}
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