Przewijanie okna w JavaScript

<SCRIPT language=JavaScript>
<!-- Begin
var isNS=(document.layers);
var _all=(isNS)? '' : 'all.' ;
var _style=(isNS)? '' : '.style' ;
var _visible=(isNS)? 'show' : 'visible';
var w_x, w_y, item, okscroll=false, godown;
function init(){
item=eval('document.'+_all+'item'+_style);
getwindowsize();
item.visibility=_visible;
scrollpage();
}
function getwindowsize() {
w_x=(isNS)? window.innerWidth-5 : document.body.clientWidth;
w_y=(isNS)? window.innerHeight : document.body.clientHeight;
(isNS)? item.clip.width=42: item.width=42;
(isNS)? item.clip.height=20 : item.height=20;
moveitem();
}
function resizeNS() {
setTimeout('document.location.reload()',400);
}
function moveitem() {
if (isNS) {
item.moveTo((pageXOffset+w_x-70),(w_y+pageYOffset-50))
}else{
item.pixelLeft=document.body.scrollLeft+w_x-70;
item.pixelTop=w_y+document.body.scrollTop-50;
   }
}
window.onload=init;
(isNS) ? window.onresize=resizeNS : window.onresize=getwindowsize ;
function scrollpage() {
status = '';
if (okscroll) {
if (godown) {
(isNS)? window.scrollBy(0,20) : window.scrollBy(0,20) ;
} else {
(isNS)? window.scrollBy(0,-20) : window.scrollBy(0,-20) ;
   }
}
moveitem();
setTimeout('scrollpage()', 40);
}
//  End -->
</SCRIPT>

<DIV id=item><A onmouseover="okscroll=true; godown=true"
onmouseout=okscroll=false href="javascript:void(0)"><IMG height=16
src="down.gif" width=16 border=0></A><A
onmouseover="okscroll=true; godown=false" onmouseout=okscroll=false
href="javascript:void(0)"><IMG src="up.gif" border=0></A> </DIV>