empty

Creates an Observable that emits no items to the Observer and immediately emits a complete notification.

Deprecation Notes

Replaced with the EMPTY constant or scheduled (e.g. scheduled([], scheduler)). Will be removed in v8.

empty(scheduler?: SchedulerLike)

Parameters

scheduler

Optional. Default is undefined. A SchedulerLike to use for scheduling the emission of the complete notification.

Description

Just emits 'complete', and nothing else.

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 mergeMap.

Examples

Emit the number 7, then complete

import { empty } from 'rxjs';
import { startWith } from 'rxjs/operators';

const result = empty().pipe(startWith(7));
result.subscribe(x => console.log(x));

// Outputs
// 7

Map and flatten only odd numbers to the sequence 'a', 'b', 'c'

import { empty, interval, of } from 'rxjs';
import { mergeMap } from 'rxjs/operators';

const interval$ = interval(1000);
const result = interval$.pipe(
  mergeMap(x => x % 2 === 1 ? of('a', 'b', 'c') : empty()),
);
result.subscribe(x => console.log(x));

// Results in the following to the console:
// x is equal to the count on the interval, e.g. (0, 1, 2, 3, ...)
// x will occur every 1000ms
// if x % 2 is equal to 1, print a, b, c (each on its own)
// if x % 2 is not equal to 1, nothing will be output

See Also

• Observable
• never
• of
• throwError