from

RxJS 5 from

by Echyzen

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/6.2.1/rxjs.umd.js"></script>
<script src="https://rawgit.com/eu81273/jsfiddle-console/master/console.js"></script>

JavaScript

const source$ = rxjs.interval(1000)

const example$ = source$.pipe(rxjs.operators.startWith(-3,-2,-1))

example$.subscribe(val => console.log(val))