function   getTop(e)   
{   
    var   x   =   e.offsetLeft,   y   =   e.offsetTop;   
    while(e=e.offsetParent) 
    { 
       x   +=   e.offsetLeft;   
       y   +=   e.offsetTop;
    } 
    alert("x:"+x+","+"y:"+y);   
}

------解决方案--------------------

推荐一下Jquery作者John Resig自己封装的常用函数
JScript code
//获取元素相对于这个页面的x和y坐标。       
function pageX(elem){   
    return elem.offsetParent?(elem.offsetLeft+pageX(elem.offsetParent)):elem.offsetLeft;   
}   
  
function pageY(elem){   
    return elem.offsetParent?(elem.offsetTop+pageY(elem.offsetParent)):elem.offsetTop;   
}

------解决方案--------------------

JScript code

function getPosition(e)
{
var left = 0;
var top = 0;
while (e.offsetParent) {
    left += e.offsetLeft;
    top += e.offsetTop;
    e = e.offsetParent;
}
left += e.offsetLeft;
top += e.offsetTop;
return {
    x: left,
    y: top
};
}
var top = getPosition(document.getElementById("div1")).y;