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

The raceWith operator from RxJS allows us to race multiple observables against each other, and the observable that emits first wins the race. Here is an example code snippet:

index.tsx
import { interval, raceWith } from 'rxjs';
import { mapTo } from 'rxjs/operators';

const obs1$ = interval(1000).pipe(mapTo('obs1'));
const obs2$ = interval(2000).pipe(mapTo('obs2'));
const obs3$ = interval(3000).pipe(mapTo('obs3'));

raceWith(obs1$, obs2$, obs3$).subscribe(
  winner => console.log(`Observable ${winner} won the race!`)
);
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In this example, we create three observables that emit a value every 1, 2 and 3 seconds respectively. We then use the raceWith operator to race these observables against each other.

When any of the observables emits a value, the corresponding string identifier is emitted as the first value from the raceWith operator. In our case, the observable that emits first will be the one that wins the race. We then subscribe to the raceWith operator and log out the winning identifier.

This is a powerful tool for handling multiple Observables, especially when your application requires fetching data from multiple APIs or databases.