function isLogin()
{   
     request.open("Post","Default_Ajax.aspx",true);
     request.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
     request.onreadystatechange=_isLoginHelper;
     request.send("action=il");
}     
function _isLoginHelper()
{
  if(request.readyState==4)
  {
     if(request.status==200)
     {
         if(request.responseText=="yes")
         {
			 window.location="VipZone.aspx";
             return true;
         }
         else
         {
              alert("对不起,没找到您的登陆信息,请先登陆!");
              return false;
		 }
     }
     else
     {
         alert("内部服务器错误:"+request.statusText+"，请重试或请联系网站管理员!");
          return false;
      }
   }
}