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- import { OuterSubscriber } from '../OuterSubscriber';
- import { subscribeToResult } from '../util/subscribeToResult';
- export const defaultThrottleConfig = {
- leading: true,
- trailing: false
- };
- /**
- * Emits a value from the source Observable, then ignores subsequent source
- * values for a duration determined by another Observable, then repeats this
- * process.
- *
- * <span class="informal">It's like {@link throttleTime}, but the silencing
- * duration is determined by a second Observable.</span>
- *
- * <img src="./img/throttle.png" width="100%">
- *
- * `throttle` 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 by calling the `durationSelector` function with the source value,
- * which returns the "duration" Observable. When the duration Observable emits a
- * value or completes, the timer is disabled, and this process repeats for the
- * next source value.
- *
- * @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.throttle(ev => Rx.Observable.interval(1000));
- * result.subscribe(x => console.log(x));
- *
- * @see {@link audit}
- * @see {@link debounce}
- * @see {@link delayWhen}
- * @see {@link sample}
- * @see {@link throttleTime}
- *
- * @param {function(value: T): SubscribableOrPromise} durationSelector A function
- * that receives a value from the source Observable, for computing the silencing
- * duration for each source value, returned as an Observable or a Promise.
- * @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 throttle
- * @owner Observable
- */
- export function throttle(durationSelector, config = defaultThrottleConfig) {
- return (source) => source.lift(new ThrottleOperator(durationSelector, config.leading, config.trailing));
- }
- class ThrottleOperator {
- constructor(durationSelector, leading, trailing) {
- this.durationSelector = durationSelector;
- this.leading = leading;
- this.trailing = trailing;
- }
- call(subscriber, source) {
- return source.subscribe(new ThrottleSubscriber(subscriber, this.durationSelector, this.leading, this.trailing));
- }
- }
- /**
- * We need this JSDoc comment for affecting ESDoc
- * @ignore
- * @extends {Ignored}
- */
- class ThrottleSubscriber extends OuterSubscriber {
- constructor(destination, durationSelector, _leading, _trailing) {
- super(destination);
- this.destination = destination;
- this.durationSelector = durationSelector;
- this._leading = _leading;
- this._trailing = _trailing;
- this._hasTrailingValue = false;
- }
- _next(value) {
- if (this.throttled) {
- if (this._trailing) {
- this._hasTrailingValue = true;
- this._trailingValue = value;
- }
- }
- else {
- const duration = this.tryDurationSelector(value);
- if (duration) {
- this.add(this.throttled = subscribeToResult(this, duration));
- }
- if (this._leading) {
- this.destination.next(value);
- if (this._trailing) {
- this._hasTrailingValue = true;
- this._trailingValue = value;
- }
- }
- }
- }
- tryDurationSelector(value) {
- try {
- return this.durationSelector(value);
- }
- catch (err) {
- this.destination.error(err);
- return null;
- }
- }
- /** @deprecated internal use only */ _unsubscribe() {
- const { throttled, _trailingValue, _hasTrailingValue, _trailing } = this;
- this._trailingValue = null;
- this._hasTrailingValue = false;
- if (throttled) {
- this.remove(throttled);
- this.throttled = null;
- throttled.unsubscribe();
- }
- }
- _sendTrailing() {
- const { destination, throttled, _trailing, _trailingValue, _hasTrailingValue } = this;
- if (throttled && _trailing && _hasTrailingValue) {
- destination.next(_trailingValue);
- this._trailingValue = null;
- this._hasTrailingValue = false;
- }
- }
- notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) {
- this._sendTrailing();
- this._unsubscribe();
- }
- notifyComplete() {
- this._sendTrailing();
- this._unsubscribe();
- }
- }
- //# sourceMappingURL=throttle.js.map
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