RxJS Playground
A blank canvas to play / experiment with RxJS: https://github.com/Reactive-Extensions/RxJS
HTML
<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/4.0.7/rx.all.js"></script>
Babel + JSX
const xs = Rx.Observable
.interval(0)
//.share();
xs.combineLatest(xs, (a,b) => [a,b])
.filter(ab => ab[1] > ab[0])
.take(1)
.subscribe(ab => alert(ab));