72 lines
2.4 KiB
JavaScript
72 lines
2.4 KiB
JavaScript
import { Observable } from '../Observable';
|
|
/**
|
|
* We need this JSDoc comment for affecting ESDoc.
|
|
* @extends {Ignored}
|
|
* @hide true
|
|
*/
|
|
export class EmptyObservable extends Observable {
|
|
constructor(scheduler) {
|
|
super();
|
|
this.scheduler = scheduler;
|
|
}
|
|
/**
|
|
* Creates an Observable that emits no items to the Observer and immediately
|
|
* emits a complete notification.
|
|
*
|
|
* <span class="informal">Just emits 'complete', and nothing else.
|
|
* </span>
|
|
*
|
|
* <img src="./img/empty.png" width="100%">
|
|
*
|
|
* This static operator is useful for creating a simple Observable that only
|
|
* emits the complete notification. It can be used for composing with other
|
|
* Observables, such as in a {@link mergeMap}.
|
|
*
|
|
* @example <caption>Emit the number 7, then complete.</caption>
|
|
* var result = Rx.Observable.empty().startWith(7);
|
|
* result.subscribe(x => console.log(x));
|
|
*
|
|
* @example <caption>Map and flatten only odd numbers to the sequence 'a', 'b', 'c'</caption>
|
|
* var interval = Rx.Observable.interval(1000);
|
|
* var result = interval.mergeMap(x =>
|
|
* x % 2 === 1 ? Rx.Observable.of('a', 'b', 'c') : Rx.Observable.empty()
|
|
* );
|
|
* result.subscribe(x => console.log(x));
|
|
*
|
|
* // Results in the following to the console:
|
|
* // x is equal to the count on the interval eg(0,1,2,3,...)
|
|
* // x will occur every 1000ms
|
|
* // if x % 2 is equal to 1 print abc
|
|
* // if x % 2 is not equal to 1 nothing will be output
|
|
*
|
|
* @see {@link create}
|
|
* @see {@link never}
|
|
* @see {@link of}
|
|
* @see {@link throw}
|
|
*
|
|
* @param {Scheduler} [scheduler] A {@link IScheduler} to use for scheduling
|
|
* the emission of the complete notification.
|
|
* @return {Observable} An "empty" Observable: emits only the complete
|
|
* notification.
|
|
* @static true
|
|
* @name empty
|
|
* @owner Observable
|
|
*/
|
|
static create(scheduler) {
|
|
return new EmptyObservable(scheduler);
|
|
}
|
|
static dispatch(arg) {
|
|
const { subscriber } = arg;
|
|
subscriber.complete();
|
|
}
|
|
/** @deprecated internal use only */ _subscribe(subscriber) {
|
|
const scheduler = this.scheduler;
|
|
if (scheduler) {
|
|
return scheduler.schedule(EmptyObservable.dispatch, 0, { subscriber });
|
|
}
|
|
else {
|
|
subscriber.complete();
|
|
}
|
|
}
|
|
}
|
|
//# sourceMappingURL=EmptyObservable.js.map
|