mapTo

RxJS 5 mapTo

by superj80820

HTML

<script src="https://npmcdn.com/@reactivex/[email protected]/dist/global/Rx.umd.js"></script>
<div id="output">1</div>
<button id="plus" type="button">+1</button>
<button id="minus" type="button">-1</button>

JavaScript

Rx.Observable.fromEvent(document.getElementById('plus'), 'click')
  .mapTo(1)
  .merge(
    Rx.Observable.fromEvent(document.getElementById('minus'), 'click')
      .mapTo(-1)
  )
  .scan((total, now) => total + now)
  .subscribe(value => {
    document.getElementById('output').innerText = value;
  })