Web page floating Ads JS code

<div id= "ad" style= "Position:absolute" >
<a href= "http://www.jzread.com/" target= "_blank" >
<img src= "http://www.jzread.com/skin/default/imga/w300ad.gif" border= "0" >
</a>
</div>
<script>
var x = 300,y = 144
var xin = true, Yin = True
var step = 1
var delay = ten
var obj=docu Ment.getelementbyid ("ad")
function Floatad () {
var l=t=0
var r= document.body.clientwidth-obj.offsetwidth
var B = document.body.clientheight-obj.offsetheight
Obj.style.left = x + document.body.scrollLeft
Obj.style.top = y + document.body.scrollTop
x = x + step* (xin?1:-1)
if (x < L) {Xin = true; x = L}
if (x > R) { Xin = false; x = R}
y = y + step* (yin?1:-1)
if (Y < T) {Yin = true; y = T}
if (Y > B) {yin = false; y = b}
}
V Ar itl= setinterval ("Floatad ()", delay)
Obj.onmouseover=function () {clearinterval (ITL)}
obj.onmouseout= function () {Itl=sEtinterval ("Floatad ()", delay)}
</script>
<script language=javascript>
<!--
if ( self.name== ' main ') top.location = "index.php";

var alertinput = "Please enter: NN";
function Login (form) {
var mesg = "";
if (Form.log_user.value = = "") MESG + = "User n";
if (Form.log_pwd.value = = "") MESG + + = "Password n";
if (MESG!= "") {
MESG = Alertinput + mesg;
alert (MESG);
return false;
}
Form.submit ();
}

function Chk_enterkey (form) {
if (window.event.keycode==13) {
Login (form);
}
}
-->
</SCRIPT>