JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/5.0.1/Rx.js"></script>

JavaScript

var source = Rx.Observable.from(['a','b','c','d',2])
            .zip(Rx.Observable.interval(500), (x,y) => x);

var example = source
                .map(x => x.toUpperCase())
                .retry(1);

example.subscribe({
    next: (value) => { console.log(value); },
    error: (err) => { console.log('Error: ' + err); },
    complete: () => { console.log('complete'); }
});