cookie操作的问题

可能会有兼容性问题 火狐下面应该是可以的，我自己测试通过<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<style>
body{
font-size:12px;
}
.div{
position:relative;
top: 0;
left:50%;
display: block;
width: 240px;
padding:10px 0;
height:100px;
background: #fcb34c;
z-index: 1;
}
.div_x{
width: 0;
height: 0;
border-left: 10px solid transparent;
border-right: 10px solid transparent;
border-top: 10px solid #fcb34c;
    position:absolute;
left:50%;
bottom:-10px;
margin-left:-5px;
}.div_close{
width:30px;
height:30px;
position:absolute;
right:2px;
top:2px;
background:#FFF;
    cursor:pointer;
}</style>
<script type="text/javascript">
function Cookie(key,value)
{
    this.key=key;
    if(value!=null)
    {
        this.value=escape(value);
    }
    this.expiresTime=null;
    this.domain=null;
    this.path="/";
    this.secure=null;
}
Cookie.prototype.setValue=function(value){this.value=escape(value);}
Cookie.prototype.getValue=function(){return (this.value);}Cookie.prototype.setExpiresTime=function(time){this.expiresTime=time;}
Cookie.prototype.getExpiresTime=function(){return this.expiresTime;}Cookie.prototype.setDomain=function(domain){this.domain=domain;}
Cookie.prototype.getDomain=function(){return this.domain;}Cookie.prototype.setPath=function(path){this.path=path;}
Cookie.prototype.getPath=function(){return this.path;}Cookie.prototype.Write=function(v)
{
    if(v!=null)
    {
        this.setValue(v);
    }
    var ck=this.key+"="+this.value;
    if(this.expiresTime!=null)
    {
        try
        {
            ck+=";expires="+this.expiresTime.toUTCString();;
        }
        catch(err)
        {
            alert("expiresTime参数错误");
        }
    }
    if(this.domain!=null)
    {
        ck+=";domain="+this.domain;
    }
    if(this.path!=null)
    {
        ck+=";path="+this.path;
    }
    if(this.secure!=null)
    {
        ck+=";secure";
    }
    document.cookie=ck;
}
Cookie.prototype.Read=function()
{
    try
    {
        var cks=document.cookie.split("; ");
        var i=0;
        for(i=0;i <cks.length;i++)
        {
            var ck=cks[i];
            var fields=ck.split("=");
            if(fields[0]==this.key)
            {
                this.value=fields[1];
                return (this.value);
            }
        }
        return null;
    }
    catch(err)
    {
        alert("cookie读取错误");
        return null;
    }
}
</script>
<script type="text/javascript" language="javascript">
 window.onload=function(){
  var ck=new Cookie("HasLoaded");  //每个页面的new Cookie名HasLoaded不能相同
  if(ck.Read()==null){//未加载过，Cookie内容为空
      alert("首次打开页面");
    
     //设置保存时间
     var dd = new Date();
     dd = new Date(dd.getYear() + 1900, dd.getMonth(), dd.getDate());
     dd.setDate(dd.getDate() + 365);
     ck.setExpiresTime(dd);      ck.Write("true");  //设置Cookie。只要IE不关闭，Cookie就一直存在
  }
  else{//Cookie存在，表示页面是被刷新的
   alert("页面刷新");
   document.getElementById('div').style.display = "none";
  }
 }
</script>
</head><body>
<div class="div" id="div">
 
 <div class="div_close">
   关闭
 </div>
</div></body>
</html>