Visual Scoring of Main Content via Javascript

score.js

/*
 * Really all this does so far is give a score based on how much the element protrudes off the center.  Center content is usually the focus
*/

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

function score(doc) { 
    var left = getOffset(doc).left; 
    var right = doc.offsetWidth + left; 
    var mid = document.width / 2; 
    return ((mid - left) <  (right - mid)) ? (mid - left) : (right - mid); 
}