| import { Subscriber } from '../Subscriber'; |
| import { async } from '../scheduler/async'; |
| /** |
| * Emits the most recently emitted value from the source Observable within |
| * periodic time intervals. |
| * |
| * <span class="informal">Samples the source Observable at periodic time |
| * intervals, emitting what it samples.</span> |
| * |
| * <img src="./img/sampleTime.png" width="100%"> |
| * |
| * `sampleTime` periodically looks at the source Observable and emits whichever |
| * value it has most recently emitted since the previous sampling, unless the |
| * source has not emitted anything since the previous sampling. The sampling |
| * happens periodically in time every `period` milliseconds (or the time unit |
| * defined by the optional `scheduler` argument). The sampling starts as soon as |
| * the output Observable is subscribed. |
| * |
| * @example <caption>Every second, emit the most recent click at most once</caption> |
| * var clicks = Rx.Observable.fromEvent(document, 'click'); |
| * var result = clicks.sampleTime(1000); |
| * result.subscribe(x => console.log(x)); |
| * |
| * @see {@link auditTime} |
| * @see {@link debounceTime} |
| * @see {@link delay} |
| * @see {@link sample} |
| * @see {@link throttleTime} |
| * |
| * @param {number} period The sampling period expressed 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 sampling. |
| * @return {Observable<T>} An Observable that emits the results of sampling the |
| * values emitted by the source Observable at the specified time interval. |
| * @method sampleTime |
| * @owner Observable |
| */ |
| export function sampleTime(period, scheduler = async) { |
| return (source) => source.lift(new SampleTimeOperator(period, scheduler)); |
| } |
| class SampleTimeOperator { |
| constructor(period, scheduler) { |
| this.period = period; |
| this.scheduler = scheduler; |
| } |
| call(subscriber, source) { |
| return source.subscribe(new SampleTimeSubscriber(subscriber, this.period, this.scheduler)); |
| } |
| } |
| /** |
| * We need this JSDoc comment for affecting ESDoc. |
| * @ignore |
| * @extends {Ignored} |
| */ |
| class SampleTimeSubscriber extends Subscriber { |
| constructor(destination, period, scheduler) { |
| super(destination); |
| this.period = period; |
| this.scheduler = scheduler; |
| this.hasValue = false; |
| this.add(scheduler.schedule(dispatchNotification, period, { subscriber: this, period })); |
| } |
| _next(value) { |
| this.lastValue = value; |
| this.hasValue = true; |
| } |
| notifyNext() { |
| if (this.hasValue) { |
| this.hasValue = false; |
| this.destination.next(this.lastValue); |
| } |
| } |
| } |
| function dispatchNotification(state) { |
| let { subscriber, period } = state; |
| subscriber.notifyNext(); |
| this.schedule(state, period); |
| } |
| //# sourceMappingURL=sampleTime.js.map |