publish-connectable.ts

import { concat, ConnectableObservable, of, race, timer } from "rxjs";
import { delay, mapTo, publish } from "rxjs/operators";

const source = of(42).pipe(delay(100));
const published = source.pipe(
  publish()
) as ConnectableObservable<number>;
const composed = race(
  published,
  concat(timer(10).pipe(mapTo(54)), published)
);
composed.subscribe(value => console.log(value));
published.connect();