docs(operators): write comprehensive JSDoc on audit()

src/operator/audit.ts

@@ -9,8 +9,42 @@ import {OuterSubscriber} from '../OuterSubscriber';
 import {subscribeToResult} from '../util/subscribeToResult';
 
 /**
- * @param durationSelector
- * @return {Observable<R>|WebSocketSubject<T>|Observable<T>}
+ * Ignores source values for a duration determined by another Observable, then
+ * emits the most recent value from the source Observable, then repeats this
+ * process.
+ *
+ * <span class="informal">It's like {@link auditTime}, but the silencing
+ * duration is determined by a second Observable.</span>
+ *
+ * <img src="./img/audit.png" width="100%">
+ *
+ * `audit` is similar to `throttle`, but emits the last value from the silenced
+ * time window, instead of the first value. `audit` 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 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, then the most
+ * recent source value is emitted on the output Observable, 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.audit(ev => Rx.Observable.interval(1000));
+ * result.subscribe(x => console.log(x));
+ *
+ * @see {@link auditTime}
+ * @see {@link debounce}
+ * @see {@link delayWhen}
+ * @see {@link sample}
+ * @see {@link throttle}
+ *
+ * @param {function(value: T): Observable|Promise} durationSelector A function
+ * that receives a value from the source Observable, for computing the silencing
+ * duration, returned as an Observable or a Promise.
+ * @return {Observable<T>} An Observable that performs rate-limiting of
+ * emissions from the source Observable.
  * @method audit
  * @owner Observable
  */