title: jqueryUI autoComplete, how to check if no data returned back
body: <p>I got jQueryUI AutoComplete working.  now I need to add another alert box, if there's no result returned back. I want to say</p>
  
  <pre><code>alert("sorry, no data found");
  </code></pre>
  
  <p>I am not sure how to add it to my existing code.</p>
  
  <pre><code>        $("#searchbox").autocomplete({
              source: function (request, response) {
                  $.ajax({
                      url: "/Home/SearchIngredients",
                      dataType: 'json',
                      data: request,
                      success: function (data) {
                          response(data.map(function (value) {
                              return {
                                  'label': value.Value,
                                  'value': value.Value,
                                  'id': value.Id
                              };
                          }));
                      }
                  });
              },
              minLength: 2,
              select: function (event, ui) {
                  $("#searchItemId").val(ui.item.id);
                  $("#searchItemName").val(ui.item.value);
              }
          });
  </code></pre>