JS获取鼠标位置、当前元素所在位置

//获取元素的绝对位置，大小。 参数js对象
function getElAbsolute(elem) {
var t = elem.offsetTop;
var l = elem.offsetLeft;
var w = elem.offsetWidth;
var h = elem.offsetHeight;
elem = elem.offsetParent;
while (elem) {
t += elem.offsetTop;
l += elem.offsetLeft;
elem = elem.offsetParent;
};
return {
top: t,
left: l,
width: w,
height: h
};
}
//兼容各种浏览器的,获取鼠标真实位置
function mousePosition(ev) {
if (!ev) ev = window.event;
if (ev.pageX || ev.pageY) {
return { x: ev.pageX, y: ev.pageY };
}
return {
x: ev.clientX + document.documentElement.scrollLeft - document.body.clientLeft,
y: ev.clientY + document.documentElement.scrollTop - document.body.clientTop
};
}