@reactivex/rxjs
Version:
Reactive Extensions for modern JavaScript
179 lines • 6.9 kB
JavaScript
"use strict";
var __extends = (this && this.__extends) || (function () {
var extendStatics = function (d, b) {
extendStatics = Object.setPrototypeOf ||
({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
return extendStatics(d, b);
}
return function (d, b) {
extendStatics(d, b);
function __() { this.constructor = d; }
d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
})();
Object.defineProperty(exports, "__esModule", { value: true });
var Subscriber_1 = require("../Subscriber");
var async_1 = require("../scheduler/async");
var throttle_1 = require("./throttle");
/**
* Emits a value from the source Observable, then ignores subsequent source
* values for `duration` milliseconds, then repeats this process.
*
* <span class="informal">Lets a value pass, then ignores source values for the
* next `duration` milliseconds.</span>
*
* 
*
* `throttleTime` emits the source Observable values on the output Observable
* when its internal timer is disabled, and ignores source values when the timer
* is enabled. Initially, the timer is disabled. As soon as the first source
* value arrives, it is forwarded to the output Observable, and then the timer
* is enabled. After `duration` milliseconds (or the time unit determined
* internally by the optional `scheduler`) has passed, the timer is disabled,
* and this process repeats for the next source value. Optionally takes a
* {@link SchedulerLike} for managing timers.
*
* ## Examples
*
* #### Limit click rate
*
* Emit clicks at a rate of at most one click per second
* ```ts
* import { fromEvent } from 'rxjs';
* import { throttleTime } from 'rxjs/operators';
*
* const clicks = fromEvent(document, 'click');
* const result = clicks.pipe(throttleTime(1000));
* result.subscribe(x => console.log(x));
* ```
*
* #### Double Click
*
* The following example only emits clicks which happen within a subsequent
* delay of 400ms of the previous click. This for example can emulate a double
* click. It makes use of the `trailing` parameter of the throttle configuration.
*
* ```ts
* import { fromEvent, asyncScheduler } from 'rxjs';
* import { throttleTime, withLatestFrom } from 'rxjs/operators';
*
* // defaultThottleConfig = { leading: true, trailing: false }
* const throttleConfig = {
* leading: false,
* trailing: true
* }
*
* const click = fromEvent(document, 'click');
* const doubleClick = click.pipe(
* throttleTime(400, asyncScheduler, throttleConfig)
* );
*
* doubleClick.subscribe((throttleValue: Event) => {
* console.log(`Double-clicked! Timestamp: ${throttleValue.timeStamp}`);
* });
* ```
*
* If you enable the `leading` parameter in this example, the output would be the primary click and
* the double click, but restricts additional clicks within 400ms.
*
* @see {@link auditTime}
* @see {@link debounceTime}
* @see {@link delay}
* @see {@link sampleTime}
* @see {@link throttle}
*
* @param {number} duration Time to wait before emitting another value after
* emitting the last value, measured in milliseconds or the time unit determined
* internally by the optional `scheduler`.
* @param {SchedulerLike} [scheduler=async] The {@link SchedulerLike} to use for
* managing the timers that handle the throttling.
* @param {Object} config a configuration object to define `leading` and
* `trailing` behavior. Defaults to `{ leading: true, trailing: false }`.
* @return {Observable<T>} An Observable that performs the throttle operation to
* limit the rate of emissions from the source.
* @method throttleTime
* @owner Observable
*/
function throttleTime(duration, scheduler, config) {
if (scheduler === void 0) { scheduler = async_1.async; }
if (config === void 0) { config = throttle_1.defaultThrottleConfig; }
return function (source) { return source.lift(new ThrottleTimeOperator(duration, scheduler, config.leading, config.trailing)); };
}
exports.throttleTime = throttleTime;
var ThrottleTimeOperator = /** @class */ (function () {
function ThrottleTimeOperator(duration, scheduler, leading, trailing) {
this.duration = duration;
this.scheduler = scheduler;
this.leading = leading;
this.trailing = trailing;
}
ThrottleTimeOperator.prototype.call = function (subscriber, source) {
return source.subscribe(new ThrottleTimeSubscriber(subscriber, this.duration, this.scheduler, this.leading, this.trailing));
};
return ThrottleTimeOperator;
}());
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
var ThrottleTimeSubscriber = /** @class */ (function (_super) {
__extends(ThrottleTimeSubscriber, _super);
function ThrottleTimeSubscriber(destination, duration, scheduler, leading, trailing) {
var _this = _super.call(this, destination) || this;
_this.duration = duration;
_this.scheduler = scheduler;
_this.leading = leading;
_this.trailing = trailing;
_this._hasTrailingValue = false;
_this._trailingValue = null;
return _this;
}
ThrottleTimeSubscriber.prototype._next = function (value) {
if (this.throttled) {
if (this.trailing) {
this._trailingValue = value;
this._hasTrailingValue = true;
}
}
else {
this.add(this.throttled = this.scheduler.schedule(dispatchNext, this.duration, { subscriber: this }));
if (this.leading) {
this.destination.next(value);
}
else if (this.trailing) {
this._trailingValue = value;
this._hasTrailingValue = true;
}
}
};
ThrottleTimeSubscriber.prototype._complete = function () {
if (this._hasTrailingValue) {
this.destination.next(this._trailingValue);
this.destination.complete();
}
else {
this.destination.complete();
}
};
ThrottleTimeSubscriber.prototype.clearThrottle = function () {
var throttled = this.throttled;
if (throttled) {
if (this.trailing && this._hasTrailingValue) {
this.destination.next(this._trailingValue);
this._trailingValue = null;
this._hasTrailingValue = false;
}
throttled.unsubscribe();
this.remove(throttled);
this.throttled = null;
}
};
return ThrottleTimeSubscriber;
}(Subscriber_1.Subscriber));
function dispatchNext(arg) {
var subscriber = arg.subscriber;
subscriber.clearThrottle();
}
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