网站页面漂浮广告js代码

<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 = 10
var obj=document.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 }
}
var 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 = "请输入:nn"; 
function Login(form){
 var mesg = "";
 if(form.log_user.value == "") mesg += "用户n";
 if(form.log_pwd.value == "") mesg += "密码n";
 if(mesg != ""){
  mesg = AlertInput + mesg;
  alert(mesg);
  return false;
 }
 form.submit();
}

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