What is the withLatestFrom operator in RxJS?

Can you explain the withLatestFrom operator in RxJS?

Sure! The withLatestFrom operator combines the latest values from multiple observables whenever the source observable emits a value.

How does it differ from combineLatest?

Unlike combineLatest, which emits every time any of the source observables emit, withLatestFrom only emits when the source observable emits.

Can you give me a code example?

Of course! Here's a simple example:

import { interval } from 'rxjs';
import { withLatestFrom } from 'rxjs/operators';

const source$ = interval(1000);
const latest$ = interval(2000);

source$.pipe(
  withLatestFrom(latest$)
).subscribe(([sourceValue, latestValue]) => {
  console.log(`Source: ${sourceValue}, Latest: ${latestValue}`);
});

What are some common use cases for withLatestFrom?

Common use cases include scenarios where you want to react to the latest state or value from another observable, like form inputs or user actions.