var box = document.getElementById('box'),

    x, y, w;

​

x = box.getBoundingClientRect().left;

y = box.getBoundingClientRect().top;

​

if (box.getBoundingClientRect().width) {

  w = box.getBoundingClientRect().width; // for modern browsers

} else {

  w = box.offsetWidth; // for oldIE

}

​

document.getElementById('result').innerHTML = '<strong>This box is</strong>:<br>' + x + 'px from the left<br>' + y + 'px from the top<br>' + w + 'px wide<br>';