function getElementLeft(element) {
var actualLeft = element.offsetLeft;
var current = element.offsetParent;
while (current !== null) {
actualLeft += current.offsetLeft;
current = current.offsetParent;
}
return actualLeft;
}

function getElementTop(element) {
var actualTop = element.offsetTop;
var current = element.offsetParent;
while (current !== null) {
actualTop += current.offsetTop;
current = current.offsetParent;
}
return actualTop;
}

javascript获取html标记的的绝对定位值