$.ajax({

                                type: "post",

                                contentType: "application/json",

                                url: /DCSRequestName.asmx/GetName",

                                data: "{str:'" + $("#txtName").val() + "'}",

                                dataType: "json",

                                success: function (result) {

                                    $("#lstAgent").empty();

                                    if (result.d != null){                                        $.each(result.d, function (index, data) {

                                            $("#lstAgent").append("<option value='" + index + "'>" + data + "</option>");

                                            if ($("#txtName").val() == data)

                                                $("#lstAgent").val(index);

                                        });

                                        $("#lstAgent").attr("size", $("#lstAgent option").length + 1);