debounceTime.js
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"use strict";
var __extends = (this && this.__extends) || function (d, b) {
for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
function __() { this.constructor = d; }
d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
var Subscriber_1 = require('../Subscriber');
var async_1 = require('../scheduler/async');
/**
* Emits a value from the source Observable only after a particular time span
* has passed without another source emission.
*
* <span class="informal">It's like {@link delay}, but passes only the most
* recent value from each burst of emissions.</span>
*
* <img src="./img/debounceTime.png" width="100%">
*
* `debounceTime` 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 emits that only when `dueTime` enough time has passed
* without any other value appearing on the source Observable. If a new value
* appears before `dueTime` silence occurs, the previous value will be dropped
* and will not be emitted on the output Observable.
*
* This is a rate-limiting operator, because it is impossible for more than one
* value to be emitted in any time window of duration `dueTime`, but it is also
* a delay-like operator since output emissions do not occur at the same time as
* they did on the source Observable. Optionally takes a {@link Scheduler} for
* managing timers.
*
* @example <caption>Emit the most recent click after a burst of clicks</caption>
* var clicks = Rx.Observable.fromEvent(document, 'click');
* var result = clicks.debounceTime(1000);
* result.subscribe(x => console.log(x));
*
* @see {@link auditTime}
* @see {@link debounce}
* @see {@link delay}
* @see {@link sampleTime}
* @see {@link throttleTime}
*
* @param {number} dueTime The timeout duration in milliseconds (or the time
* unit determined internally by the optional `scheduler`) for the window of
* time required to wait for emission silence before emitting the most recent
* source value.
* @param {Scheduler} [scheduler=async] The {@link Scheduler} to use for
* managing the timers that handle the timeout for each value.
* @return {Observable} An Observable that delays the emissions of the source
* Observable by the specified `dueTime`, and may drop some values if they occur
* too frequently.
* @method debounceTime
* @owner Observable
*/
function debounceTime(dueTime, scheduler) {
if (scheduler === void 0) { scheduler = async_1.async; }
return this.lift(new DebounceTimeOperator(dueTime, scheduler));
}
exports.debounceTime = debounceTime;
var DebounceTimeOperator = (function () {
function DebounceTimeOperator(dueTime, scheduler) {
this.dueTime = dueTime;
this.scheduler = scheduler;
}
DebounceTimeOperator.prototype.call = function (subscriber, source) {
return source.subscribe(new DebounceTimeSubscriber(subscriber, this.dueTime, this.scheduler));
};
return DebounceTimeOperator;
}());
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
var DebounceTimeSubscriber = (function (_super) {
__extends(DebounceTimeSubscriber, _super);
function DebounceTimeSubscriber(destination, dueTime, scheduler) {
_super.call(this, destination);
this.dueTime = dueTime;
this.scheduler = scheduler;
this.debouncedSubscription = null;
this.lastValue = null;
this.hasValue = false;
}
DebounceTimeSubscriber.prototype._next = function (value) {
this.clearDebounce();
this.lastValue = value;
this.hasValue = true;
this.add(this.debouncedSubscription = this.scheduler.schedule(dispatchNext, this.dueTime, this));
};
DebounceTimeSubscriber.prototype._complete = function () {
this.debouncedNext();
this.destination.complete();
};
DebounceTimeSubscriber.prototype.debouncedNext = function () {
this.clearDebounce();
if (this.hasValue) {
this.destination.next(this.lastValue);
this.lastValue = null;
this.hasValue = false;
}
};
DebounceTimeSubscriber.prototype.clearDebounce = function () {
var debouncedSubscription = this.debouncedSubscription;
if (debouncedSubscription !== null) {
this.remove(debouncedSubscription);
debouncedSubscription.unsubscribe();
this.debouncedSubscription = null;
}
};
return DebounceTimeSubscriber;
}(Subscriber_1.Subscriber));
function dispatchNext(subscriber) {
subscriber.debouncedNext();
}
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