import $ from 'jquery';
import Rx from 'rxjs/Rx';

const source1$ = Rx.Observable.interval(2000)
.map(v=>'s1 ' + v);
const source2$ = Rx.Observable.interval(1500)
.map(v=>'s2 ' + v);

Rx.Observable.merge(source1$, source2$)
.take(15).subscribe(v=>console.log(v));