。net 后台将List数据转换为json后 前台js 调用

//C#后台代码  public string ReturnType()        {            DataTable TypeList = ClassOrAboutBLL.Instance.Type();            List<ClassOrAboutModel> list = new List<ClassOrAboutModel>();            foreach (DataRow item in TypeList.Rows)            {                ClassOrAboutModel model = new ClassOrAboutModel();                model.ClassOrAboutType = item["ClassOrAbout"].ToString();                model.Type = item["Type"].ToString();                model.TypeDescibe = item["TypeDescibe"].ToString();                list.Add(model);            }            DataContractJsonSerializer json = new DataContractJsonSerializer(list.GetType());            string szJson = "";            using (MemoryStream stream = new MemoryStream())            {                json.WriteObject(stream, list);                szJson = Encoding.UTF8.GetString(stream.ToArray());            }            return szJson;        }

 function changetype(){           var Type = <%=ReturnType() %>;                     //Type[i].TypeDescibe             //Type[i].Type                                          }