JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://unpkg.com/@reactivex/rxjs@5.0.3/dist/global/Rx.js"></script>

JavaScript

const source = Rx.Observable.interval(1000).take(3);

const example = source
                .do(x => console.log('do log: ' + x))
                .map(x => x + 1);

example.subscribe((x) => {
    console.log('subscription log: ' + x)
})