Angular 6 run code every 5 seconds but it emits for 1st time

Question

I want to run my code as soon as it gets into my component and repeat the logic every 5 seconds

Here is my code, I used the interval of rxjs

ngOnInit() {
  const ticker = interval(5000);
  ticker.subscribe(() => {
    this.calculateTime();
  });
}

But the issue here is that for the code runs

1st time at 5s 
2nd time at 10s

But I want it to run as

1st time at 0s 
2nd time at 5s
3rs time at 10s

This is how I tacked:

ngOnInit() {
  const ticker = interval(5000);
  this.calculateTime();
  ticker.subscribe(() => {
    this.calculateTime();
  });
}

If you notice I called this.calculateTime(); twice once before ticker and 2nd inside ticker.

Is there a better solution using interval ? If not may be an alternative to interval

Possible duplicate of [How to get an observable to return data immediately and every 5 seconds thereafter](https://stackoverflow.com/questions/36612945/how-to-get-an-observable-to-return-data-immediately-and-every-5-seconds-thereaft) — Vahid, Jan 20 '19 at 15:08

score 3 · Accepted Answer · answered Jan 20 '19 at 15:11

3

You can use timer. It does the same as interval but adds the functionality you need: controlling the first emission.

ngOnInit() {
  const ticker = timer(0, 5000);
  ticker.subscribe(() => {
    this.calculateTime();
  });
}

answered Jan 20 '19 at 15:11

a better oliver

Kristian Vitozev · Answer 2 · 2019-01-20T16:10:55.300

0

Try the following:

import { startWith } from 'rxjs/operators';
// ....
const ticker = interval(5000).pipe(
     startWith(0)
);

edited Jan 20 '19 at 16:10

answered Jan 20 '19 at 15:07

Kristian Vitozev

[ts] Property 'startWith' does not exist on type 'Observable'. [2339] – Varun Sukheja Jan 20 '19 at 15:22
Which version of RxJS are you using? – Kristian Vitozev Jan 20 '19 at 15:27
I am using Rxjs 6.3.3 – Varun Sukheja Jan 20 '19 at 15:54
See the updated answer, however the accepted answer is a better approach. – Kristian Vitozev Jan 20 '19 at 16:01
still same isse – Varun Sukheja Jan 20 '19 at 16:04
Did you import the `startWith` operator? – Kristian Vitozev Jan 20 '19 at 16:04
Yes, I did so. I copied your code and replaced it with my code. – Varun Sukheja Jan 20 '19 at 16:09
Sorry, I had a typo, inside the`pipe()` it should be `startWith(0)`, without a dot before it. – Kristian Vitozev Jan 20 '19 at 16:11

2 Answers2