正在尝试查找javascript元素's在屏幕上的位置..在webkit浏览器上无法正常工作

这是我现在使用的代码。在webkit浏览器（Chrome和Safari）上，如果页面被滚动，则不会考虑页面的滚动量。我需要帮助重新设计该功能以适用于Webkit浏览器。我不想加载jQuery，因为它将用于web小部件，我需要降低文件大小。谢谢大家！

function __getIEVersion() {
    var rv = -1; // Return value assumes failure.
    if (navigator.appName == 'Microsoft Internet Explorer') {
        var ua = navigator.userAgent;
        var re = new RegExp("MSIE ([0-9]{1,}['.0-9]{0,})");
        if (re.exec(ua) != null)
            rv = parseFloat(RegExp.$1);
    }
    return rv;
}
function __getOperaVersion() {
    var rv = 0; // Default value
    if (window.opera) {
        var sver = window.opera.version();
        rv = parseFloat(sver);
    }
    return rv;
}
var __userAgent = navigator.userAgent;
var __isIE =  navigator.appVersion.match(/MSIE/) != null;
var __IEVersion = __getIEVersion();
var __isIENew = __isIE && __IEVersion >= 8;
var __isIEOld = __isIE && !__isIENew;
var __isFireFox = __userAgent.match(/firefox/i) != null;
var __isFireFoxOld = __isFireFox && ((__userAgent.match(/firefox'/2./i) != null) || 
    (__userAgent.match(/firefox'/1./i) != null));
var __isFireFoxNew = __isFireFox && !__isFireFoxOld;
var __isWebKit =  navigator.appVersion.match(/WebKit/) != null;
var __isChrome =  navigator.appVersion.match(/Chrome/) != null;
var __isOpera =  window.opera != null;
var __operaVersion = __getOperaVersion();
var __isOperaOld = __isOpera && (__operaVersion < 10);
function __parseBorderWidth(width) {
    var res = 0;
    if (typeof(width) == "string" && width != null && width != "" ) {
        var p = width.indexOf("px");
        if (p >= 0) {
            res = parseInt(width.substring(0, p));
        }
        else {
            //do not know how to calculate other values 
        //(such as 0.5em or 0.1cm) correctly now
            //so just set the width to 1 pixel
            res = 1; 
        }
    }
    return res;
}
//returns border width for some element
function __getBorderWidth(element) {
    var res = new Object();
    res.left = 0; res.top = 0; res.right = 0; res.bottom = 0;
    if (window.getComputedStyle) {
        //for Firefox
        var elStyle = window.getComputedStyle(element, null);
        res.left = parseInt(elStyle.borderLeftWidth.slice(0, -2));  
        res.top = parseInt(elStyle.borderTopWidth.slice(0, -2));  
        res.right = parseInt(elStyle.borderRightWidth.slice(0, -2));  
        res.bottom = parseInt(elStyle.borderBottomWidth.slice(0, -2));  
    }
    else {
        //for other browsers
        res.left = __parseBorderWidth(element.style.borderLeftWidth);
        res.top = __parseBorderWidth(element.style.borderTopWidth);
        res.right = __parseBorderWidth(element.style.borderRightWidth);
        res.bottom = __parseBorderWidth(element.style.borderBottomWidth);
    }
    return res;
}
//returns the absolute position of some element within document
function getElementAbsolutePos(element) {
    var res = new Object();
    res.x = 0; res.y = 0;
    if (element !== null) { 
        if (element.getBoundingClientRect) {
            var viewportElement = document.documentElement;  
            var box = element.getBoundingClientRect();
            var scrollLeft = viewportElement.scrollLeft;
            var scrollTop = viewportElement.scrollTop;
            res.x = box.left + scrollLeft;
            res.y = box.top + scrollTop;
        }
        else { //for old browsers
            res.x = element.offsetLeft;
            res.y = element.offsetTop;
            var parentNode = element.parentNode;
            var borderWidth = null;
            while (offsetParent != null) {
                res.x += offsetParent.offsetLeft;
                res.y += offsetParent.offsetTop;
                var parentTagName = 
                    offsetParent.tagName.toLowerCase(); 
                if ((__isIEOld && parentTagName != "table") || 
                    ((__isFireFoxNew || __isChrome) && 
                        parentTagName == "td")) {           
                    borderWidth = kGetBorderWidth
                            (offsetParent);
                    res.x += borderWidth.left;
                    res.y += borderWidth.top;
                }
                if (offsetParent != document.body && 
                offsetParent != document.documentElement) {
                    res.x -= offsetParent.scrollLeft;
                    res.y -= offsetParent.scrollTop;
                }

                //next lines are necessary to fix the problem 
                //with offsetParent
                if (!__isIE && !__isOperaOld || __isIENew) {
                    while (offsetParent != parentNode && 
                        parentNode !== null) {
                        res.x -= parentNode.scrollLeft;
                        res.y -= parentNode.scrollTop;
                        if (__isFireFoxOld || __isWebKit) 
                        {
                            borderWidth = 
                             kGetBorderWidth(parentNode);
                            res.x += borderWidth.left;
                            res.y += borderWidth.top;
                        }
                        parentNode = parentNode.parentNode;
                    }    
                }
                parentNode = offsetParent.parentNode;
                offsetParent = offsetParent.offsetParent;
            }
        }
    }
    var scrOfX = 0, scrOfY = 0;
    if( typeof( window.pageYOffset ) == 'number' ) {
        //Netscape compliant
        scrOfY = window.pageYOffset;
        scrOfX = window.pageXOffset;
    } else if( document.body && ( document.body.scrollLeft || document.body.scrollTop ) ) {
        //DOM compliant
        scrOfY = document.body.scrollTop;
        scrOfX = document.body.scrollLeft;
    } else if( document.documentElement && ( document.documentElement.scrollLeft || document.documentElement.scrollTop ) ) {
        //IE6 standards compliant mode
        scrOfY = document.documentElement.scrollTop;
        scrOfX = document.documentElement.scrollLeft;
    }

    return res;
}