es6/operator/throttleTime.js

import { Subscriber } from '../Subscriber';
import { async } from '../scheduler/async';
import { defaultThrottleConfig } from './throttle';
/**
 * 从源 Observable 中发出一个值，然后在 `duration` 毫秒内忽略随后发出的源值，
 * 然后重复此过程。
 *
 * <span class="informal">让一个值通过，然后在接下来的 `duration` 毫秒内忽略源值。</span>
 *
 * <img src="./img/throttleTime.png" width="100%">
 *
 * 当 `throttle` 的内部定时器禁用时，它会在输出 Observable 上发出源 Observable 的值，
 * 并当定时器启用时忽略源值。最开始时，定时器是禁用的。一旦第一个源值达到，它会被转发
 * 到输出 Observable ，然后启动定时器。在 `duration` 毫秒(或由可选的 `scheduler`
 * 内部确定的时间单位)后，定时器会被禁用，并且下一个源值也是重复此过程。可选择性地
 * 接收一个 {@link IScheduler} 用来管理定时器。
 *
 * @example <caption>以每秒最多点击一次的频率发出点击事件</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 在发出一个最新的值后，到再发出另外一个值之间的等待时间，
 * 以毫秒为单位或以可选的 `scheduler` 内部决定的时间单位来衡量。
 * @param {Scheduler} [scheduler=async] 调度器( {@link IScheduler} )，用来
 * 管理处理节流的定时器。
 * @return {Observable<T>} 该 Observable 执行节流操作，以限制源 Observable 的
 * 发送频率。
 * @method throttleTime
 * @owner Observable
 */
export function throttleTime(duration, scheduler = async, config = defaultThrottleConfig) {
    return this.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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