code: function (event) {
              var el = $(event.target).closest(".select2-result-selectable");
              if (el.length > 0 && !el.is(".select2-highlighted")) {
                  var choices = this.findHighlightableChoices();
                  this.highlight(choices.index(el));
              } else if (el.length == 0) {
                  // if we are over an unselectable item remove all highlights
                  this.removeHighlight();
              }
          }
docs: abstract