auditTime.ts

import { async } from '../scheduler/async';
import { audit } from './audit';
import { timer } from '../observable/timer';
import { MonoTypeOperatorFunction, SchedulerLike } from '../types';

/**
 * Ignores source values for `duration` milliseconds, then emits the most recent
 * value from the source Observable, then repeats this process.
 *
 * <span class="informal">When it sees a source value, it ignores that plus
 * the next ones for `duration` milliseconds, and then it emits the most recent
 * value from the source.</span>
 *
 * ![](auditTime.png)
 *
 * `auditTime` is similar to `throttleTime`, but emits the last value from the
 * silenced time window, instead of the first value. `auditTime` emits the most
 * recent value from the source Observable on the output Observable as soon as
 * its internal timer becomes disabled, and ignores source values while the
 * timer is enabled. Initially, the timer is disabled. As soon as the first
 * source value arrives, the timer is enabled. After `duration` milliseconds (or
 * the time unit determined internally by the optional `scheduler`) has passed,
 * the timer is disabled, then the most recent source value is emitted on the
 * output Observable, and this process repeats for the next source value.
 * Optionally takes a {@link SchedulerLike} for managing timers.
 *
 * ## Example
 *
 * Emit clicks at a rate of at most one click per second
 * ```ts
 * import { fromEvent, auditTime } from 'rxjs';
 *
 * const clicks = fromEvent(document, 'click');
 * const result = clicks.pipe(auditTime(1000));
 * result.subscribe(x => console.log(x));
 * ```
 *
 * @see {@link audit}
 * @see {@link debounceTime}
 * @see {@link delay}
 * @see {@link sampleTime}
 * @see {@link throttleTime}
 *
 * @param {number} duration Time to wait before emitting the most recent source
 * value, measured in milliseconds or the time unit determined internally
 * by the optional `scheduler`.
 * @param {SchedulerLike} [scheduler=async] The {@link SchedulerLike} to use for
 * managing the timers that handle the rate-limiting behavior.
 * @return A function that returns an Observable that performs rate-limiting of
 * emissions from the source Observable.
 */
export function auditTime<T>(duration: number, scheduler: SchedulerLike = async): MonoTypeOperatorFunction<T> {
  return audit(() => timer(duration, scheduler));
}