Demystifying RxJS, Part II: MergeMap test

02-06-demystifying-rxjs-mergemap-test.ts

function sleep(ms: number) {
  return new Promise(resolve => setTimeout(resolve, ms));
}

function createInner(x: number) {
  return new Observable(obs => {
    (async () => {
      for (let i = 0; i < 3; i++) {
        if (i > 0) await sleep(500);
        obs.next(10 * x);
      }
      obs.complete();
    })();
  });
}

const outer = new Observable(obs => {
  (async () => {
    obs.next(1);
    await sleep(800);
    obs.next(3);
    await sleep(3000);
    obs.complete();
  })();
});

outer
  .pipe(mergeMap(createInner))
  .subscribe(x => console.log("[mergeMap] outer:", x));