medium-rxjs-publish.ts

import { concat, defer, Observable, of } from "rxjs";
import { delay, publish } from "rxjs/operators";

function random() {
  return Math.floor(Math.random() * 100);
}

const source = concat(
  defer(() => of(random())),
  defer(() => of(random())).pipe(delay(1))
);

function observer(name: string) {
  return {
    next: (value: number) => console.log(`observer ${name}: ${value}`),
    complete: () => console.log(`observer ${name}: complete`)
  };
}

const p = source.pipe(publish());
p.subscribe(observer("a"));
p.connect();
p.subscribe(observer("b"));
setTimeout(() => p.subscribe(observer("c")), 10);