medium-rxjs-publish.ts

import { Observable } from "rxjs/Observable";
import "rxjs/add/observable/concat";
import "rxjs/add/observable/defer";
import "rxjs/add/observable/of";
import "rxjs/add/operator/delay";
import "rxjs/add/operator/publish";

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

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

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

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