How to populate dropdownlist with JSON data as ajax response in jQuery

Question

I am working on a j2ee application. In my application I have a drop-down list(or Select element). I want to populate this drop-down list with JSON data as a Ajax response.

Answer 1

                                        <%----%>
                                        
                                    

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     $(document).ready(function () {
                $.ajax({
                    type: "POST",
                    url: "AjaxCallGrid.asmx/GetDropDown",
                    dataType: "json",
                    contentType: "application/json; charset=utf-8",
                    success: function (result) {
                        $('.DropDown').empty();
                        $('.DropDown').append("---Select---");
                        $.each(result.d, function (key, value) {
                            $('.DropDown').append($("").val(value.iD).html(value.firstName));
                        });
                    }
                });
            });
    -------------------------------------------------------------------------
     [WebMethod]
        public  List GetDropDown()
        {
            DataTable dt = new DataTable();
            List result = new List();
            using (SqlConnection con = new SqlConnection(@"Data Source=DOS-PC\MARJI;Initial Catalog=examples;Integrated Security=True"))
            {
                using (SqlCommand cmd = new SqlCommand("select id,firstname from Students ", con))
                {
                    con.Open();
                    SqlDataAdapter da = new SqlDataAdapter(cmd);
                    da.Fill(dt);
                    if (dt.Rows.Count > 0)
                    {
                        for (int i = 0; i < dt.Rows.Count; i++)
                        {
                            result.Add(new Students
                            {
                                iD = Convert.ToInt32(dt.Rows[i]["id"].ToString()),
                                firstName = dt.Rows[i]["firstname"].ToString()
                            }
                                );
                        }
                    }
                    return result;
                }
            }