| 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; |
| } |
| } |
| _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 |