repeat

Returns an Observable that will resubscribe to the source stream when the source stream completes.

repeat<T>(countOrConfig?: number | RepeatConfig): MonoTypeOperatorFunction<T>

Parameters

countOrConfig

number | RepeatConfig

Optional. Default is undefined.

Returns

MonoTypeOperatorFunction<T>

Description

Repeats all values emitted on the source. It's like retry, but for non error cases.

Repeat will output values from a source until the source completes, then it will resubscribe to the source a specified number of times, with a specified delay. Repeat can be particularly useful in combination with closing operators like take, takeUntil, first, or takeWhile, as it can be used to restart a source again from scratch.

Repeat is very similar to retry, where retry will resubscribe to the source in the error case, but repeat will resubscribe if the source completes.

Note that repeat will not catch errors. Use retry for that.

• repeat(0) returns an empty observable
• repeat() will repeat forever
• repeat({ delay: 200 }) will repeat forever, with a delay of 200ms between repetitions.
• repeat({ count: 2, delay: 400 }) will repeat twice, with a delay of 400ms between repetitions.
• repeat({ delay: (count) => timer(count * 1000) }) will repeat forever, but will have a delay that grows by one second for each repetition.

Example

Repeat a message stream

import { of, repeat } from 'rxjs';

const source = of('Repeat message');
const result = source.pipe(repeat(3));

result.subscribe(x => console.log(x));

// Results
// 'Repeat message'
// 'Repeat message'
// 'Repeat message'

Repeat 3 values, 2 times

import { interval, take, repeat } from 'rxjs';

const source = interval(1000);
const result = source.pipe(take(3), repeat(2));

result.subscribe(x => console.log(x));

// Results every second
// 0
// 1
// 2
// 0
// 1
// 2

Defining two complex repeats with delays on the same source. Note that the second repeat cannot be called until the first repeat as exhausted it's count.

import { defer, of, repeat } from 'rxjs';

const source = defer(() => {
   return of(`Hello, it is ${new Date()}`)
});

source.pipe(
   // Repeat 3 times with a delay of 1 second between repetitions
   repeat({
     count: 3,
     delay: 1000,
   }),

   // *Then* repeat forever, but with an exponential step-back
   // maxing out at 1 minute.
   repeat({
     delay: (count) => timer(Math.min(60000, 2 ^ count * 1000))
   })
)

See Also

• repeatWhen
• retry