Lo script da inserire in html
<SCRIPT>
<!-- // Copyright (c) 1999 P. Gehrig and U. Dudli// If you add this script to a script-library
// you have to add a link to www.24fun.ch.
var timer
function initiate() {
timer=setTimeout("initiate()",20)
}
// -->
</SCRIPT>
<body onLoad="initiate()">
<center>
<div id="obj1" style="position:absolute;left:0px;top:0px;width:95px;height:95px;visibility:hidden;"><img
src="topoballa.gif" border=0 height=120 width=120></div>
<div id="obj2" style="position:absolute;left:0px;top:0px;width:95px;height:95px;visibility:hidden;"><img
src="logoanatrasp.gif" border=0 height=95 width=95></div>
<script>
var isNS = (navigator.appName == "Netscape" && parseInt(navigator.appVersion) >= 4);
var div1 = (isNS) ? document.obj1 : document.all.obj1.style;
var div2 = (isNS) ? document.obj2 : document.all.obj2.style;
var objet;var coord;var coordb = 800;
objet = new Array(div1,div2);coord = new Array();
coord[0]=50;coord[1]=50;
function placeObj(i,px,py) {
objet[i].left=px;
objet[i].top=py;
}
function voirObj(i) {
objet[i].visibility="visible";
}
function cacheObj(i) {
objet[i].visibility="hidden";
}
var userAgent=navigator.appName + " " + navigator.appVersion;
var agentInfo=userAgent.substring(0, 12);
if(agentInfo >= "Netscape 4.0")
{
document.captureEvents(Event.MOUSEMOVE);
var Xpos = 50;var Ypos = 50;
function MouveA(evnt) {
Xpos = evnt.pageX;Ypos = evnt.pageY;
}
document.onMouseMove = MouveA;
}
else {
var Xpos = 50;var Ypos = 50;
function MouveB() {
ofy=document.body.scrollTop;ofx=document.body.scrollLeft;
Xpos = event.clientX+ofx;Ypos = event.clientY+ofy;
}
document.onmousemove = MouveB;
}
function vole() {
x0=coord[0];y0=coord[1];ex=Xpos;ey=Ypos
reelx=x0+0.04;reely=y0+0.04;
rx=reelx;ry=reely;
rx+=(ex-rx)*0.04;ry+=(ey-ry)*0.04;
reelx=rx;reely=ry;
x0=Math.round(reelx);y0=Math.round(reely);
coord[0]=x0;coord[1]=y0;
if (x0<=Xpos) {voirObj(0);cacheObj(1);}
else {voirObj(1);cacheObj(0);}
placeObj(0,x0-22,y0-37);placeObj(1,x0-22,y0-37);
setTimeout("vole()", 5);
}
vole();
</script>