Drag and drop with RxJS

RxJSDragDrop.js

const body = document.body;
const draggableElement = document.getElementById('drag');

const mouseDown$ = Rx.Observable.fromEvent(draggableElement, 'mousedown');
const mouseUp$ = Rx.Observable.fromEvent(body, 'mouseup');
const mouseMove$ = Rx.Observable.fromEvent(body, 'mousemove');

mouseDown$
  .map(event => mouseMove$.takeUntil(mouseUp$))
  .concatAll()
  .map(event => ({ x: event.clientX, y: event.clientY }))
  .subscribe(pos => {
    draggableElement.style.left = pos.x + 'px';
    draggableElement.style.top = pos.y + 'px';
  });