how to provide an alert when there is no record in the table?

Question

When i click on submit button, Based on hidden field ID we are getting the value from database and loaded in the table. if value is present the table should be loaded otherwise i need to display alert as 'there is no record'.Currently the value is loaded in the table but it is does not show an alert when there is no record.

<a href="javascript:void(0)" id="InteractGeneric"><b>Interact Generic List</b></a>

<div class="table-responsive" id="findValue" style="display:none;height:500px;">
                        <table id="example" class="display table table-striped table-bordered" cellspacing="0" width="100%;">
                            <thead>
                                <tr>
                                    <th>S#</th>
                                    <th>Generic Name</th>
                                    <th>Interact Generic</th>
                                    <th>Interact Description</th>

                            </thead>
                            <tbody></tbody>
                        </table>
                    </div>

Script:

<script>
        $(document).ready(function () {
            $('#InteractGeneric').click(function () {
                var GenericID = $("#hdnGenericID").val();
                $("#example tbody tr").remove();

                $.ajax({

                    type: 'POST',

                    url: '@Url.Action("GenericInteractionNewDetails")',
                    dataType: 'json',
                    data: { GenericID: GenericID },
                    success: function (data) {
                        var items = '';
                        $.each(data.GenList, function (i, item) {
                            if (data.GenList == undefined)
                            {
                                alert("Nothing Found");
                            }

                            $("#findValue").show();

                            var rows = "<tr>"
                            + "<td>" + (i + 1) + "</td>"
                            + "<td>" + item.GenericName + "</td>"
                            + "<td>" + item.GenSuperClass + "</td>"
                            + "<td>" + item.GenClass + "</td>"
                            + "</tr>";
                            $('#example tbody').append(rows);
                        });
                    },
                    error: function (ex) {
                        var r = jQuery.parseJSON(response.responseText);
                        alert("Message: " + r.Message); d
                        alert("StackTrace: " + r.StackTrace);
                        alert("ExceptionType: " + r.ExceptionType);
                    }
                });
                return false;
            });
        });

    </script>

Controller:

[HttpPost]
        public ActionResult GenericInteractionNewDetails(int GenericID)
        {
            List<GenericMaster> GenList = dGMSP.GenericInteractionDetails(GenericID);
            var data = new { GenList = GenList };
            return Json(data, JsonRequestBehavior.AllowGet);
        }

Alert does not work:

if (data.GenList == undefined)
    {
      alert("Nothing Found");
    }

Answer 1

If the response data is an array,

    if (data.GenList.length === 0) {
       alert("No items found")
    }

If the response is an object,

   if (jQuery.isEmptyObject(YOUR_OBJECT)) {
       alert("No item found")
   }

Answer 2

You can use like this

if (!data.GenList.length)
{
  alert("Nothing Found");
}