RxJS - concatAll
HTML
<script src="//cdnjs.cloudflare.com/ajax/libs/rxjs/5.1.1/Rx.js"></script>
JavaScript
console.log('Start');
//emit a value every 2 seconds
const router = Rx.Observable.interval(2000).map(val => 'Title router '+val);
const internal = Rx.Observable.interval(2000).delay(5000).map(val => 'Title internal'+val);
const example = Rx.Observable.merge(
router.takeUntil(internal)
)
.merge(internal);
const subscribe = example.subscribe(title => console.log(title));