text: /* global mouseTracker */
  
  (function () {
  
    var mouse = mouseTracker({
      element: document.getElementById('box')
    });
  
    var el = document.createElement('pre');
    document.body.appendChild(el);
  
    function update () {
      el.innerHTML = mouse.x + ', ' + mouse.y;
    }
  
    update();
    mouse.onmove = update;
  
  })();
  