Javascript Frage...

<script language="JavaScript1.2">


var slideshow_width=640 
var slideshow_height=480 
var pause=3000


var fadeimages=new Array()
fadeimages[0]="black.gif"
fadeimages[1]="johanna.jpg"
fadeimages[2]="black.gif"


var preloadedimages=new Array()
for (p=0;p<fadeimages.length;p++){
preloadedimages[p]=new Image()
preloadedimages[p].src=fadeimages[p]
}


var ie4=document.all&&navigator.userAgent.indexOf("Opera")==-1
var dom=document.getElementById&&navigator.userAgent.indexOf("Opera")==-1


if (ie4||dom)
document.write('<div style="position:relative;width:'+slideshow_width+';height:'+slideshow_height+';overflow:hidden"><div  id="canvas0" style="position:absolute;width:'+slideshow_width+';height:'+slideshow_height+';top:0;filter:alpha(opacity=10);-moz-opacity:10"></div><div id="canvas1" style="position:absolute;width:'+slideshow_width+';height:'+slideshow_height+';top:0;filter:alpha(opacity=10);-moz-opacity:10"></div></div>')
else
document.write('<img name="defaultslide" src="'+fadeimages[0]+'">')


var curpos=10
var degree=10
var curcanvas="canvas0"
var curimageindex=0
var nextimageindex=1




function fadepic(){
if (curpos<100){
curpos+=10
if (tempobj.filters)
tempobj.filters.alpha.opacity=curpos
else if (tempobj.style.MozOpacity)
tempobj.style.MozOpacity=curpos/100
}
else{
clearInterval(dropslide)
nextcanvas=(curcanvas=="canvas0")? "canvas0" : "canvas1"
tempobj=ie4? eval("document.all."+nextcanvas) : document.getElementById(nextcanvas)
tempobj.innerHTML='<img src="'+fadeimages[nextimageindex]+'">'
nextimageindex=(nextimageindex<fadeimages.length-1)? nextimageindex+1 : 0
setTimeout("rotateimage()",pause)
}
}


function rotateimage(){
if (ie4||dom){
resetit(curcanvas)
var crossobj=tempobj=ie4? eval("document.all."+curcanvas) : document.getElementById(curcanvas)
crossobj.style.zIndex++
var temp='setInterval("fadepic()",50)'
dropslide=eval(temp)
curcanvas=(curcanvas=="canvas0")? "canvas1" : "canvas0"
}
else
document.images.defaultslide.src=fadeimages[curimageindex]
curimageindex=(curimageindex<fadeimages.length-1)? curimageindex+1 : 0
}


function resetit(what){
curpos=10
var crossobj=ie4? eval("document.all."+what) : document.getElementById(what)
if (crossobj.filters)
crossobj.filters.alpha.opacity=curpos
else if (crossobj.style.MozOpacity)
crossobj.style.MozOpacity=curpos/100
}


function startit(){
var crossobj=ie4? eval("document.all."+curcanvas) : document.getElementById(curcanvas)
crossobj.innerHTML='<img src="'+fadeimages[curimageindex]+'">'
rotateimage()
}


if (ie4||dom)
window.onload=startit
else
setInterval("rotateimage()",pause)


</script>