/*

以下代码是尝试进行AJAX用户注册练习

参考资料：http://www.alixixi.com/Dev/Web/ajax/ajax2/2007/2007032530345.html

修改人：蔡刚

时间：2008-5-28

*/

// 直接先创建 XMLHttpRequest 对象，
var XmlRequest = false;
   try {
     XmlRequest = new XMLHttpRequest();
   } catch (trymicrosoft) {
     try {
       XmlRequest = new ActiveXObject("Msxml2.XMLHTTP");
     } catch (othermicrosoft) {
       try {
         XmlRequest = new ActiveXObject("Microsoft.XMLHTTP");
       } catch (failed) {
         XmlRequest = false;
       }  
     }
   }

   if (!XmlRequest)
      alert("对不起，您的浏览器版本过抵不支持 XMLHttpRequest 对象，\n 部分功能可能不能正常使用，请升级您的浏览器!");
    function getCustomerInfo() {
	   //检测合法性
         //var username =document.reg.username.value;
         //var url = "User_center_check.asp?action=cusername&username=" + escape(username);
		 var url = "index_check.asp";
     XmlRequest.open("GET", url, true);
     XmlRequest.onreadystatechange = updatePage;
     XmlRequest.send(null);
   }

   function updatePage() {
	  
   if (XmlRequest.readyState < 4) 
       {
		  document.getElementById("check_username").innerHTML="<img src=images/gif-0537.gif width=16 height=16 vspace=0  align=absmiddle hspace=2/>正在加载最新信息...";
 		   }
   if (XmlRequest.readyState == 4)
      { 
         if (XmlRequest.status == 200) 
	          {
                var response = XmlRequest.responseText;
                     document.getElementById("check_username").innerHTML = response;
               } else
                     alert("status is " + XmlRequest.status);
      }
 }