@reactivex/rxjs/dist-compat/cjs/src/internal/operators/debounce.js

Reactive Extensions for modern 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 innerSubscribe_1 = require("../innerSubscribe");
/**
 * 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>
 *
 * ![](debounce.png)
 *
 * `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
 * Emit the most recent click after a burst of clicks
 * ```ts
 * import { fromEvent, interval } from 'rxjs';
 * import { debounce } from 'rxjs/operators';
 *
 * const clicks = fromEvent(document, 'click');
 * const result = clicks.pipe(debounce(() => 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
 */
function debounce(durationSelector) {
    return function (source) { return source.lift(new DebounceOperator(durationSelector)); };
}
exports.debounce = debounce;
var DebounceOperator = /** @class */ (function () {
    function DebounceOperator(durationSelector) {
        this.durationSelector = durationSelector;
    }
    DebounceOperator.prototype.call = function (subscriber, source) {
        return source.subscribe(new DebounceSubscriber(subscriber, this.durationSelector));
    };
    return DebounceOperator;
}());
/**
 * We need this JSDoc comment for affecting ESDoc.
 * @ignore
 * @extends {Ignored}
 */
var DebounceSubscriber = /** @class */ (function (_super) {
    __extends(DebounceSubscriber, _super);
    function DebounceSubscriber(destination, durationSelector) {
        var _this = _super.call(this, destination) || this;
        _this.durationSelector = durationSelector;
        _this.hasValue = false;
        return _this;
    }
    DebounceSubscriber.prototype._next = function (value) {
        try {
            var result = this.durationSelector.call(this, value);
            if (result) {
                this._tryNext(value, result);
            }
        }
        catch (err) {
            this.destination.error(err);
        }
    };
    DebounceSubscriber.prototype._complete = function () {
        this.emitValue();
        this.destination.complete();
    };
    DebounceSubscriber.prototype._tryNext = function (value, duration) {
        var subscription = this.durationSubscription;
        this.value = value;
        this.hasValue = true;
        if (subscription) {
            subscription.unsubscribe();
            this.remove(subscription);
        }
        subscription = innerSubscribe_1.innerSubscribe(duration, new innerSubscribe_1.SimpleInnerSubscriber(this));
        if (subscription && !subscription.closed) {
            this.add(this.durationSubscription = subscription);
        }
    };
    DebounceSubscriber.prototype.notifyNext = function () {
        this.emitValue();
    };
    DebounceSubscriber.prototype.notifyComplete = function () {
        this.emitValue();
    };
    DebounceSubscriber.prototype.emitValue = function () {
        if (this.hasValue) {
            var value = this.value;
            var subscription = this.durationSubscription;
            if (subscription) {
                this.durationSubscription = undefined;
                subscription.unsubscribe();
                this.remove(subscription);
            }
            // This must be done *before* passing the value
            // along to the destination because it's possible for
            // the value to synchronously re-enter this operator
            // recursively if the duration selector Observable
            // emits synchronously
            this.value = undefined;
            this.hasValue = false;
            _super.prototype._next.call(this, value);
        }
    };
    return DebounceSubscriber;
}(innerSubscribe_1.SimpleOuterSubscriber));
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