117 lines
4.3 KiB
JavaScript
117 lines
4.3 KiB
JavaScript
import { OuterSubscriber } from '../OuterSubscriber';
|
|
import { subscribeToResult } from '../util/subscribeToResult';
|
|
/**
|
|
* Emits a value from the source Observable only after a particular time span
|
|
* determined by another Observable has passed without another source emission.
|
|
*
|
|
* <span class="informal">It's like {@link debounceTime}, but the time span of
|
|
* emission silence is determined by a second Observable.</span>
|
|
*
|
|
* <img src="./img/debounce.png" width="100%">
|
|
*
|
|
* `debounce` delays values emitted by the source Observable, but drops previous
|
|
* pending delayed emissions if a new value arrives on the source Observable.
|
|
* This operator keeps track of the most recent value from the source
|
|
* Observable, and spawns a duration Observable by calling the
|
|
* `durationSelector` function. The value is emitted only when the duration
|
|
* Observable emits a value or completes, and if no other value was emitted on
|
|
* the source Observable since the duration Observable was spawned. If a new
|
|
* value appears before the duration Observable emits, the previous value will
|
|
* be dropped and will not be emitted on the output Observable.
|
|
*
|
|
* Like {@link debounceTime}, this is a rate-limiting operator, and also a
|
|
* delay-like operator since output emissions do not necessarily occur at the
|
|
* same time as they did on the source Observable.
|
|
*
|
|
* @example <caption>Emit the most recent click after a burst of clicks</caption>
|
|
* var clicks = Rx.Observable.fromEvent(document, 'click');
|
|
* var result = clicks.debounce(() => Rx.Observable.interval(1000));
|
|
* result.subscribe(x => console.log(x));
|
|
*
|
|
* @see {@link audit}
|
|
* @see {@link debounceTime}
|
|
* @see {@link delayWhen}
|
|
* @see {@link throttle}
|
|
*
|
|
* @param {function(value: T): SubscribableOrPromise} durationSelector A function
|
|
* that receives a value from the source Observable, for computing the timeout
|
|
* duration for each source value, returned as an Observable or a Promise.
|
|
* @return {Observable} An Observable that delays the emissions of the source
|
|
* Observable by the specified duration Observable returned by
|
|
* `durationSelector`, and may drop some values if they occur too frequently.
|
|
* @method debounce
|
|
* @owner Observable
|
|
*/
|
|
export function debounce(durationSelector) {
|
|
return (source) => source.lift(new DebounceOperator(durationSelector));
|
|
}
|
|
class DebounceOperator {
|
|
constructor(durationSelector) {
|
|
this.durationSelector = durationSelector;
|
|
}
|
|
call(subscriber, source) {
|
|
return source.subscribe(new DebounceSubscriber(subscriber, this.durationSelector));
|
|
}
|
|
}
|
|
/**
|
|
* We need this JSDoc comment for affecting ESDoc.
|
|
* @ignore
|
|
* @extends {Ignored}
|
|
*/
|
|
class DebounceSubscriber extends OuterSubscriber {
|
|
constructor(destination, durationSelector) {
|
|
super(destination);
|
|
this.durationSelector = durationSelector;
|
|
this.hasValue = false;
|
|
this.durationSubscription = null;
|
|
}
|
|
_next(value) {
|
|
try {
|
|
const result = this.durationSelector.call(this, value);
|
|
if (result) {
|
|
this._tryNext(value, result);
|
|
}
|
|
}
|
|
catch (err) {
|
|
this.destination.error(err);
|
|
}
|
|
}
|
|
_complete() {
|
|
this.emitValue();
|
|
this.destination.complete();
|
|
}
|
|
_tryNext(value, duration) {
|
|
let subscription = this.durationSubscription;
|
|
this.value = value;
|
|
this.hasValue = true;
|
|
if (subscription) {
|
|
subscription.unsubscribe();
|
|
this.remove(subscription);
|
|
}
|
|
subscription = subscribeToResult(this, duration);
|
|
if (!subscription.closed) {
|
|
this.add(this.durationSubscription = subscription);
|
|
}
|
|
}
|
|
notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) {
|
|
this.emitValue();
|
|
}
|
|
notifyComplete() {
|
|
this.emitValue();
|
|
}
|
|
emitValue() {
|
|
if (this.hasValue) {
|
|
const value = this.value;
|
|
const subscription = this.durationSubscription;
|
|
if (subscription) {
|
|
this.durationSubscription = null;
|
|
subscription.unsubscribe();
|
|
this.remove(subscription);
|
|
}
|
|
this.value = null;
|
|
this.hasValue = false;
|
|
super._next(value);
|
|
}
|
|
}
|
|
}
|
|
//# sourceMappingURL=debounce.js.map
|