Jquery Ajax 调用 ashx 返回结果

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace Ctrip.Flight.Process.Site
{
    /// <summary>
    /// Summary description for json
    /// </summary>
    public class json : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            if (context.Request.Params.Count != 0)
            {
                context.Response.ContentType = "text/plain";

                if (context.Request.Params["TxtOrderId"] != null && context.Request.Params["TxtSendTicketCityName"] != null)
                {
                    int OrderId = int.Parse(context.Request.Params["TxtOrderId"].ToString());
                    string SendTicketCityName = context.Request.Params["TxtSendTicketCityName"].ToString();

                    string content = String.Format("{{\"TxtOrderId\":\"{0}\",\"TxtSendTicketCityName\":\"{1}\"}}", OrderId, SendTicketCityName);
                    context.Response.Write(content);
                }
            }
            else
            {
                context.Response.Write("no values");
            }
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}

<script type="text/javascript">

        $(function () {
            $("#ContentPlaceHolder1_BtnSearch").click(function () {
                var data =
                {
                    TxtOrderId: $("#ContentPlaceHolder1_TxtOrder").val(),
                    TxtSendTicketCityName: $("#ContentPlaceHolder1_TxtSendTicketCity").val()
                };

                $.ajax({
                    type: "POST",
                    url: "../json.ashx",
                    data: data,
                    success: function (response) {

                        alert(response);
                        var dataobj = eval("(" + response + ")"); //转换为json对象
                        alert("TxtOrderId:" + dataobj.TxtOrderId);

                    }
                })
            })
        })
    </script>