CODEWITHSUNDEEP
rxjs
user
user

Reputation: 568

Observable emit values not getting delayed

I am trying to create an observable which will emit delayed values. However the values are getting instataneously. I have created a stackblitz at https://stackblitz.com/edit/typescript-cwixas. The code is given below: 

import { of } from 'rxjs';
import { map, delay } from 'rxjs/operators';

const arr = [1,2,3,4,5];
const source = of(...arr);
const source2 = source.pipe(delay(2000));
const subscribe = source2.subscribe(val => console.log(val));

Upvotes: 2

Views: 122

Answers (1)

martin
martin

Reputation: 96959

The delay() operator just adds delay to each next value but it doesn't care whether the previous delay elapsed.

So what happens here is that of() immediately emits 5 values where all 5 are scheduled to be re-emitted by delay at the same time after 2s.

You'll have to use for example concatMap that will project each value into an Observable and wait until that completes. Only then continue with another value:

const arr = [1,2,3,4,5];
const source = of(...arr).pipe(
  concatMap(value => of(value).pipe(
    delay(2000),
  )),
);

source.subscribe(...);

Your update demo: https://stackblitz.com/edit/typescript-cknhbr?file=index.ts

Upvotes: 2

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