js ajax 传送xml dom对象到服务器

客户端代码
 1     <script>
         var isie = true;
         var xmlhttp = null;
         function createXMLHTTP() {//创建XMLXMLHttpRequest对象
             if (xmlhttp == null) {
                 if (window.XMLHttpRequest) {
                     xmlhttp = new XMLHttpRequest();
                 }
                 else {
                     xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
                 }
                 //if (xmlhttp == null) {
                 //    alert('你的浏览器不支持AJAX');
                 //}
             }
         if ($.browser.msie) {//IE浏览器
                 isie = true;
             }
             else {
                 isie = false;
             }

         }
         //创建XML文档那个对象,也是第一步
         function createDomXml() {
             var domXml = null;
         //IE浏览器创建xml dom对象
             var signs = ["Msxml2.DOMDocument.5.0", "Msxml2.DOMDocument.4.0", 

 "Msxml2.DOMDocument.3.0", "Msxml2.DOMDocument", "Microsoft.XmlDom"];
             for (var i = 0; i < signs.length; i++) {
                 try {
                     domXml = new ActiveXObject(signs[i]);
                     break;
                 }
                 catch (e) { }
             }

             //其他浏览器
             if (domXml == null)
                 domXml = document.implementation.createDocument("", "", null);
             return domXml;
         }
         //第二步：客户端获取数据写入xml文档对象里
         function createXml(dom) {
             var root = doc.createElement("root");//创建根结点
             var assign_id = doc.createElement("id");//子节点
             var assign_ans = doc.createElement("answer");//子节点
             if (isie) {
                 assign_id.text = "1";
                 assign_ans.text = "1";
             }
             else {
                 assign_id.textContent = "1";
                 assign_ans.textContent = "1";
             }

             root.appendChild(assign_id);

             root.appendChild(assign_ans);

             dom.appendChild(choose);
         }
         function submit() {
             var dom = createDomXml();
             createXMLHTTP();
             if (xmlhttp == null) {
                 alert("你的浏览器不支持ajax,请换个浏览器试试");
                 return 0;
             }
             createXml(dom);

             xmlhttp.onreadystatechange = success;
             xmlhttp.open("post", "test.aspx", true);//接收请求页面
             //xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
             xmlhttp.send(dom);
         }

         function success()//异步处理函数，当服务成功返回时
         {
             if (xmlhttp.readyState == 4) {
                 alert(xmlhttp.status);
                 if (xmlhttp.status == 200) {
                     alert(xmlhttp.responseText);
                 }
                 else {
                     alert("test error");
                 }
             }
         }
     </script>

服务器端代码 
1   protected void Page_Load(object sender, EventArgs e)
         {
         string res;
             Request.ContentEncoding = System.Text.Encoding.GetEncoding("UTF-8");
             XmlDocument xmlDoc = new XmlDocument();
             xmlDoc.Load(Request.InputStream);
             XmlNode node = xmlDoc.SelectSingleNode("choose");
             foreach (XmlNode child in node.ChildNodes)
             {
                 res + child.innerText;
             }
         Response.Write(res);
         Response.End();
         }
     }