Get the absolute, untransformed offset of HTMLElement

getOffset.js

function getAbsoluteOffset (el) {
    var _x = 0;
    var _y = 0; 
    while( el && !isNaN( el.offsetLeft ) && !isNaN( el.offsetTop ) ) {
        _x += el.offsetLeft;
        _y += el.offsetTop;
        el = el.offsetParent;
    }
    return { top: _y, left: _x };
}