ajax简单应用之动态获取服务器时间

前台aspx页面代码
<form id=form1 runat="server">
    <asp:button id=Button1 onclick=Button1_Click runat="server" Text="Button"></asp:button>利用XMLHTTP(XMLHTTPRequest)对象异步访问服务器获取数据更新页面 (IE/FireFox等支持)<br>实现效果: 动态取得服务器时间<br><br><label id=lbl></label><script>
      function GetXmlHttp()
      {
            return window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject("Microsoft.XMLHTTP");
      }
     
      function GetRequest()
      {
            var url = "GetServerTime.aspx?name=1&x=" + Math.random();
            xmlHttp = GetXmlHttp();
            xmlHttp.onreadystatechange = OnReadyStateChange;
            xmlHttp.open("GET", url, true);
            xmlHttp.send("");
      }
     
      function OnReadyStateChange()
      {
            if(xmlHttp.readyState == 4)
            {
                  document.getElementById("lbl").innerHTML = xmlHttp.responseText + "<br />更新间隔: " + interval + "ms";
            }
      }
     
      var xmlHttp;
    var interval = 1000;
    var timer = window.setInterval(GetRequest, interval);
      </script>
</form>
后台cs代码
    protected void Page_Load(object sender, EventArgs e)
    {
        if (Request.QueryString["name"] != null)
        {
            Response.Write(DateTime.Now);
            Response.End();
        }       
    }