js制作鼠标移动提示层

<script type="text/javascript">
function window.onload()
{
var tip=document.createElement("DIV")
tip.id="oTip"
with(tip.style)
{
position="absolute"
border="1px solid #363636"
backgroundColor="#C0C0C0"
font="normal 12px Tahoma"
padding="1 3 1 3"
display="none"
}
document.body.appendChild(tip)
document.onmouseover=show
document.onmouseout=hide
}
function show()
{
if(event.srcElement.alt && event.srcElement.alt!="")
{
with(oTip.style)
{
posLeft=document.body.scrollLeft+event.x+10
posTop=document.body.scrollTop+event.y+10
oTip.innerText=event.srcElement.alt
event.srcElement.alt=""
display="block"
}
}
}
function hide()
{
event.srcElement.alt=oTip.innerText
oTip.innerText=""
oTip.style.display="none"
}
</script>
<img src="http://www.google.com/intl/en_ALL/images/logo.gif" alt="图片上的提示">
<button alt="按钮上的提示">按钮</button>
<a alt="链接上的提示">链接</a>