node_modules/rxjs/_esm2015/operators/throttleTime.js

import { Subscriber } from '../Subscriber';
import { async } from '../scheduler/async';
import { defaultThrottleConfig } from './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>
 *
 * <img src="./img/throttleTime.png" width="100%">
 *
 * `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 IScheduler} for managing timers.
 *
 * @example <caption>Emit clicks at a rate of at most one click per second</caption>
 * var clicks = Rx.Observable.fromEvent(document, 'click');
 * var result = clicks.throttleTime(1000);
 * result.subscribe(x => console.log(x));
 *
 * @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 {Scheduler} [scheduler=async] The {@link IScheduler} to use for
 * managing the timers that handle the throttling.
 * @return {Observable<T>} An Observable that performs the throttle operation to
 * limit the rate of emissions from the source.
 * @method throttleTime
 * @owner Observable
 */
export function throttleTime(duration, scheduler = async, config = defaultThrottleConfig) {
    return (source) => source.lift(new ThrottleTimeOperator(duration, scheduler, config.leading, config.trailing));
}
class ThrottleTimeOperator {
    constructor(duration, scheduler, leading, trailing) {
        this.duration = duration;
        this.scheduler = scheduler;
        this.leading = leading;
        this.trailing = trailing;
    }
    call(subscriber, source) {
        return source.subscribe(new ThrottleTimeSubscriber(subscriber, this.duration, this.scheduler, this.leading, this.trailing));
    }
}
/**
 * We need this JSDoc comment for affecting ESDoc.
 * @ignore
 * @extends {Ignored}
 */
class ThrottleTimeSubscriber extends Subscriber {
    constructor(destination, duration, scheduler, leading, trailing) {
        super(destination);
        this.duration = duration;
        this.scheduler = scheduler;
        this.leading = leading;
        this.trailing = trailing;
        this._hasTrailingValue = false;
        this._trailingValue = null;
    }
    _next(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);
            }
        }
    }
    clearThrottle() {
        const 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;
        }
    }
}
function dispatchNext(arg) {
    const { subscriber } = arg;
    subscriber.clearThrottle();
}
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