how to use the observeon function from the rxjs library in javascript

To use the observeOn function from the RxJS library in JavaScript, first we need to have an observable that emits values asynchronously.

Here's an example of creating an observable that emits values asynchronously using the interval operator:

index.tsx
const { interval } = require('rxjs');

const source$ = interval(1000); // emits a value every second
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To ensure that the values emitted by our observable are observed on a specific scheduler, we can use the observeOn function.

index.tsx
const { interval } = require('rxjs');
const { observeOn } = require('rxjs/operators');
const { asapScheduler } = require('rxjs');

const source$ = interval(1000).pipe(
    observeOn(asapScheduler) // use the ASAP scheduler to observe values
);

source$.subscribe(
    value => console.log(value)
);
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In the above example, we're using the observeOn operator to ensure that values emitted by our observable are observed asynchronously on the ASAP scheduler.

The observeOn operator takes one argument, which is the scheduler that we want to use to observe values. Here we're using the built-in asapScheduler, which executes actions as soon as possible on the current event loop.

Note that the observeOn operator does not affect the execution of the observable itself — it only affects how values emitted by the observable are observed. Therefore, if you want to control the emission of values themselves, you should use operators like delay or debounceTime instead.