请问如何得到一个表格的右边框的绝对位置？

Question

<SCRIPT LANGUAGE="JavaScript">
function getP(o)
{
var r = o.getBoundingClientRect();
alert(r.top + ":" + r.left + ":" + r.bottom + ":" + r.right);
}
</SCRIPT><br>
<div style="left:100px;top:200px;" id ="aa">sdf</div>
<input type=button value="test" onclick = "getP(document.getElementById('aa'))">

Answer 1

<div style="height:300px;">
</div>
fdsafdsa<span style='background-color:#ff0000;' onclick="alert(getLeft(this))">
adfasdfasdf
</span>
<script>
function getLeft(obj)
{
    var left = obj.offsetLeft;
    var top  = obj.offsetTop;
    obj = obj.offsetParent;
    while(obj.tagName != "BODY")
    {
        left += obj.offsetLeft;
        top  += obj.offsetTop;
        obj   = obj.offsetParent;
    }
    return left;
}
</script>