diff --git a/src/internal/operators/timestamp.ts b/src/internal/operators/timestamp.ts index cdfed176a6..d4061c8c45 100644 --- a/src/internal/operators/timestamp.ts +++ b/src/internal/operators/timestamp.ts @@ -4,6 +4,34 @@ import { OperatorFunction, SchedulerLike, Timestamp as TimestampInterface } from import { map } from './map'; /** + * Attaches a timestamp to each item emitted by an observable indicating when it was emitted + * + * The `timestamp` operator maps the *source* observable stream to an object of type + * `{value: T, timestamp: R}`. The properties are generically typed. The `value` property contains the value + * and type of the *source* observable. The `timestamp` is generated by the schedulers `now` function. By + * default it uses the *async* scheduler which simply returns `Date.now()` (milliseconds since 1970/01/01 + * 00:00:00:000) and therefore is of type `number`. + * + * ![](timestamp.png) + * + * ## Example + * + * In this example there is a timestamp attached to the documents click event. + * + * ```ts + * import { fromEvent } from 'rxjs'; + * import { timestamp } from 'rxjs/operators'; + * + * const clickWithTimestamp = fromEvent(document, 'click').pipe( + * timestamp() + * ); + * + * // Emits data of type {value: MouseEvent, timestamp: number} + * clickWithTimestamp.subscribe(data => { + * console.log(data); + * }); + * ``` + * * @param scheduler * @return {Observable>|WebSocketSubject|Observable} * @method timestamp