from

RxJS 5 from

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.from([1,2,3,4,5])
//no value will pass, emit default
const example$ = source$.pipe(rxjs.operators.last(val => val > 1, 'Nothing'))

//output: 'Nothing'
const subscribe = example$.subscribe(val => console.log(val))