exhaust

exhaust operator convert higher-order Observable to first-order Observable and will ignore inner observable while previous inner Observable has not yet completed

higher-order Observable: that observable emits Observables

first-order Observable: that observable emits values, and maintains only 1 stream of observable

Example: exhaust operator

in this example you can see how to ignores the inner observable when previous inner Observable has not yet completed.

import { fromEvent, timer, interval } from 'rxjs';
import { exhaust, map, take } from 'rxjs/operators';

const projection$ = interval(500).pipe(take(6));
const source$ = timer(0, 2000).pipe(
  map(() => projection$),
  take(4)
);

const result$ = source$.pipe(exhaust());

Official Doc: rxjs.exhaust