javascript - Finding element's position relative to the document

Question

What's the easiest way to determine an elements position relative to the document/body/browser window?

Right now I'm using .offsetLeft/offsetTop, but this method only gives you the position relative to the parent element, so you need to determine how many parents to the body element, to know the position relaltive to the body/browser window/document position.

This method is also to cumbersome.

Answer 1

You can get top and left without traversing DOM like this:

function getCoords(elem) { // crossbrowser version
    var box = elem.getBoundingClientRect();

    var body = document.body;
    var docEl = document.documentElement;

    var scrollTop = window.pageYOffset || docEl.scrollTop || body.scrollTop;
    var scrollLeft = window.pageXOffset || docEl.scrollLeft || body.scrollLeft;

    var clientTop = docEl.clientTop || body.clientTop || 0;
    var clientLeft = docEl.clientLeft || body.clientLeft || 0;

    var top  = box.top +  scrollTop - clientTop;
    var left = box.left + scrollLeft - clientLeft;

    return { top: Math.round(top), left: Math.round(left) };
}