在ASP.NET中XMLHTTP.RESPONSETEXT的返回值全部是HTML代码,怎样才能只返回我RESPONSE.WRITE的内容

 

<%@ Page Language="C#" %>
<script runat="server">
    protected void Page_Load(object sender, EventArgs e)
    {
        // get the candidate user name.
        string candidateUserName = Request["UserName"];
        
        // validate
        bool isValid = false;
        if (candidateUserName.ToLower() != "dflying")
        {
            isValid = true;
        }
        
        // send out result
        Response.Clear();
        Response.Write(isValid ? "true" : "false");
        Response.Flush();
         Response.Close();
    }
</script>

 

 

 

// JScript 文件
function $(id)
{
   return document.getElementById(id);
}

//创建一个xmlhttp对象
function createXmlHttp()
{


    var xmlHttp;
    // 检测MSXMLHTTP版本，为了兼容IE各个版本
    var activeKey = new Array("MSXML2.XMLHTTP.5.0","MSXML2.XMLHTTP.4.0","MSXML2.XMLHTTP.3.0","MSXML2.XMLHTTP","Microsoft.XMLHTTP");
    if(window.ActiveXObject)
    {
       for(var i=0;i<activeKey.length;i++)
       {
          try
          {
              xmlHttp = new ActiveXObject(activeKey[i]);
              if(xmlHttp!=null)
                 return xmlHttp;
          }
          catch(error)
          {
              throw new Error("您的浏览器版本过低，请更新浏览器");
          }
       }
    }
    else if(window.XMLHttpRequest)
    {
       xmlHttp = new XMLHttpRequest();
    } 
    return xmlHttp;  
} 

function CheckUserName(name,alertstr)
{
 $("checkname").innerHTML = " loading."; 
 var url = "../test/Server.aspx?action=CheckUserName";
   var xmlhttp = createXmlHttp();
   xmlhttp.onreadystatechange=function()
   {
        if(xmlhttp.readyState==4&&xmlhttp.status==200)  
        {
        alert(xmlhttp.responseText);
        $("checkname").innerHTML = "yes"; 
             $("checkname").innerHTML = "1"+xmlhttp.responseText; 
        } 
    }
   xmlhttp.open("GET",url,true);
   xmlhttp.send(null);     
   
    /*
    
    */
  
}