图片跟随着光标

<SCRIPT LANGUAGE="JavaScript">
var image="../images/helpor.gif"
var newtop=15
var newleft=15
if (navigator.appName == "Netscape") {
layerStyleRef="layer.";
layerRef="document.layers";
styleSwitch="";
}
else
{
layerStyleRef="layer.style.";
layerRef="document.all";
styleSwitch=".style";
}

function helpor_net() {

layerName = 'iit'

eval('var curElement='+layerRef+'["'+layerName+'"]')
eval(layerRef+'["'+layerName+'"]'+styleSwitch+'.visibility="hidden"')
eval('curElement'+styleSwitch+'.visibility="visible"')
eval('newleft=document.body.clientWidth-curElement'+styleSwitch+'.pixelWidth')
eval('newtop=document.body.clientHeight-curElement'+styleSwitch+'.pixelHeight')
eval('height=curElement'+styleSwitch+'.height')
eval('width=curElement'+styleSwitch+'.width')
width=parseInt(width)
height=parseInt(height)
if (event.clientX > (document.body.clientWidth - 5 - width))
{
newleft=document.body.clientWidth + document.body.scrollLeft - 5 - width
}
else
{
newleft=document.body.scrollLeft + event.clientX
}
eval('curElement'+styleSwitch+'.pixelLeft=newleft')

if (event.clientY > (document.body.clientHeight - 5 - height))
{
newtop=document.body.clientHeight + document.body.scrollTop - 5 - height
}
else
{
newtop=document.body.scrollTop + event.clientY
}
eval('curElement'+styleSwitch+'.pixelTop=newtop')
}

document.onmousemove = helpor_net;

if (navigator.appName == "Netscape") {

}
else
{
document.write('<div ID="OuterDiv">')
document.write('<img ID="iit" src="'+image+'" STYLE="position:absolute;TOP:20pt;LEFT:20pt;Z-INDEX:20;visibility:hidden;">')
document.write('</div>')
}
</script>