Call ID in jquery

Question

I try this method to get data and also i have try jquery . In jquery i call info method

[WebMethod]
public static string info(string id) {
 try {
  string result = "";

  Entities er = new Entities();
  List < sp_web_Result > sv = er.sp_web(id).ToList();
  DataTable dt = new DataTable();
  dt.Columns.Add("No", typeof(string));
  dt.Columns.Add("Latitude", typeof(float));
  dt.Columns.Add("Longitude", typeof(float));


  foreach(var c in sv) {
   dt.Rows.Add(c.No, c.Longitude, c.Latitude);
  };
  HttpContext.Current.Session["ID"] = id;
  result = DataSetToJSON(dt);
  return result;
 }
 catch (Exception ex) {
  throw new Exception();
 }
}

jquery

 

 <script type="text/javascript">
        $(function () {

            var RegNo = '';
            var Status = '';
            var latit = '';
            var longi = '';
          var ID = '<%=Session["ID"]%>'.val();
                 var obj = {};
               obj.ID=ID;
                getdata(obj);
                return false;

        });

        function getdata(obj) {

            $.ajax({
                type: "POST",
                url: "home.aspx/info",
                contentType: "application/json;charset=utf-8",

               data: { ID: obj.ID }
                datatype: "json",
                async: true,
                cache: false,
                success: function (result) {
                   //map code


                },
                error: function (error) {
                    alert(error);
                    alert("error");
                }
            });
        }


</script>

 

try to pass id through web method in this line data:JSON.stringify(obj.ID),

when i do this there is error on console

Uncaught TypeError: "442".val is not a function

 

when i remove  .val() then this show error 

Failed to load resource: the server responded with a status of 500 (Internal Server Error)