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

The switchAll function in the rxjs library allows you to flatten an Observable-of-Observables. It subscribes to each inner Observable as it arrives, but discards the previous inner Observable if a new one arrives before the previous completes.

Here's an example of how to use switchAll:

index.tsx
import { of } from 'rxjs';
import { map, delay, switchAll } from 'rxjs/operators';

const obs = of(1000, 2000, 3000); // emits values at 1s, 2s, 3s
const source = obs.pipe(
  map(val => of(`Delayed by ${val}ms`).pipe(delay(val))),
  switchAll()
);
source.subscribe(console.log);
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In this example, we create an observable that emits the values 1000, 2000, and 3000 at 1s, 2s, and 3s respectively. We then use the map operator to create a new inner Observable for each emit that delays for the value of the previous Observable. switchAll is then used to subscribe to these inner Observables and only emit the latest observable values while canceling the previous subscriptions to the previous inner Observables. Finally, we subscribe to the switchAll source and log the emitted values to the console.

This will output the following:

index.tsx
Delayed by 1000ms
Delayed by 2000ms
Delayed by 3000ms
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