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

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JavaScript

import { switchAll as higherOrder } from '../operators/switchAll';
/**
* Converts a higher-order Observable into a first-order Observable by
* subscribing to only the most recently emitted of those inner Observables.
*
* <span class="informal">Flattens an Observable-of-Observables by dropping the
* previous inner Observable once a new one appears.</span>
*
* <img src="./img/switch.png" width="100%">
*
* `switch` subscribes to an Observable that emits Observables, also known as a
* higher-order Observable. Each time it observes one of these emitted inner
* Observables, the output Observable subscribes to the inner Observable and
* begins emitting the items emitted by that. So far, it behaves
* like {@link mergeAll}. However, when a new inner Observable is emitted,
* `switch` unsubscribes from the earlier-emitted inner Observable and
* subscribes to the new inner Observable and begins emitting items from it. It
* continues to behave like this for subsequent inner Observables.
*
* @example <caption>Rerun an interval Observable on every click event</caption>
* var clicks = Rx.Observable.fromEvent(document, 'click');
* // Each click event is mapped to an Observable that ticks every second
* var higherOrder = clicks.map((ev) => Rx.Observable.interval(1000));
* var switched = higherOrder.switch();
* // The outcome is that `switched` is essentially a timer that restarts
* // on every click. The interval Observables from older clicks do not merge
* // with the current interval Observable.
* switched.subscribe(x => console.log(x));
*
* @see {@link combineAll}
* @see {@link concatAll}
* @see {@link exhaust}
* @see {@link mergeAll}
* @see {@link switchMap}
* @see {@link switchMapTo}
* @see {@link zipAll}
*
* @return {Observable<T>} An Observable that emits the items emitted by the
* Observable most recently emitted by the source Observable.
* @method switch
* @name switch
* @owner Observable
*/
export function _switch() {
return higherOrder()(this);
}
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