API / rxjs/index

interval

Creates an Observable that emits sequential numbers every specified interval of time, on a specified SchedulerLike.

interval(period: 0 = 0, scheduler: SchedulerLike = async): Observable<number>

Parameters

period

Optional. Default is 0.

The interval size in milliseconds (by default) or the time unit determined by the scheduler's clock.
scheduler

Optional. Default is async.

The SchedulerLike to use for scheduling the emission of values, and providing a notion of "time".

Returns

Observable<number>: An Observable that emits a sequential number each time interval.

Description

Emits incremental numbers periodically in time.

interval returns an Observable that emits an infinite sequence of ascending integers, with a constant interval of time of your choosing between those emissions. The first emission is not sent immediately, but only after the first period has passed. By default, this operator uses the async SchedulerLike to provide a notion of time, but you may pass any SchedulerLike to it.

Example

Emits ascending numbers, one every second (1000ms) up to the number 3

import { interval } from 'rxjs'; import { take } from 'rxjs/operators'; const numbers = interval(1000); const takeFourNumbers = numbers.pipe(take(4)); takeFourNumbers.subscribe(x => console.log('Next: ', x)); // Logs: // Next: 0 // Next: 1 // Next: 2 // Next: 3

See Also