function getElementLeft(element)
{
var actualLeft = element.offsetLeft;
var current = element.offsetParent;
while (current!==null)
{
actualLeft += current.offsetLeft;
current = current.offsetParent;
}
return actualLeft;
}
取得元素的左偏移量；
function getElementTop(element)
{
var actualTop = element.offsetTop;
var current = element.offsetParent;
while (current!==null)
{
<span style="white-space:pre"> </span>actualTop += current.offsetTop;
current = current.offsetParent;
}
return actualTop;
}
取得元素的上偏移量；
利用offsetParent属性在Dom层次中逐级向上回溯，将每个层次偏移量合计。
