Efecto apertura javascript

Esta sencilla rutina realiza un efecto de barrido hacia arriba en forma pausada. Vale la pena darle una mirada.

<HTML>
<HEAD><TITLE>Efecto apertura</TITLE>
</HEAD>
<BODY bgColor=#ffffff leftMargin=0 rightMargin=0 topMargin=0>
<style>
<!--
.curtain{
position:absolute;
left:0;
top:0;
layer-background-color:004080;
background-color:004080;
border:0.1px solid PURPLE
}
-->
</style>
<div id="c1" class="curtain"></div><div id="c2" class="curtain"></div>
<script language="JavaScript1.2">

var speed=15
var temp=new Array()
var temp2=new Array()
if (document.layers){
for (c=1;c<=2;c++){
temp1=eval("document.c"+c+".clip")
temp21=eval("document.c"+c)
temp1.width=window.innerWidth
temp1.height=window.innerHeight/2
temp21.top=(c-1)*temp1.height
}
}
else if (document.all){
var curtainbottom=document.body.offsetHeight/2,curtaintop=0
for (c=1;c<=2;c++){
temp1=eval("document.all.c"+c+".style")
temp1.width=document.body.clientWidth
temp1.height=document.body.offsetHeight/2
temp1.top=(c-1)*parseInt(temp1.height)
}
}
function openit(){
window.scrollTo(0,0)
if (document.layers){
temp[1].bottom-=speed
temp[2].top+=speed
if (temp[1].bottom<=0)
clearInterval(stopit)
}
else if (document.all){
curtainbottom-=speed
temp[1].clip="rect(0 auto+"+curtainbottom+" 0)"
curtaintop+=speed
temp[2].clip="rect("+curtaintop+" auto auto)"
if (curtainbottom<=0)
clearInterval(stopit)
}
}
function gogo(){
stopit=setInterval("openit()",60)
}
gogo()
</script>
</body>
</html>

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