public/javascript/libs/select2.js
function (index) {
            var choices = this.findHighlightableChoices(),
                choice,
                data;

            if (arguments.length === 0) {
                return indexOf(choices.filter(".select2-highlighted")[0], choices.get());
            }

            if (index >= choices.length) index = choices.length - 1;
            if (index < 0) index = 0;

            this.results.find(".select2-highlighted").removeClass("select2-highlighted");

            choice = $(choices[index]);
            choice.addClass("select2-highlighted");

            this.ensureHighlightVisible();

            data = choice.data("select2-data");
            if (data) {
                this.opts.element.trigger({ type: "select2-highlight", val: this.id(data), choice: data });
            }
        }
function (index) {
            var choices = this.findHighlightableChoices(),
                choice,
                data;

            if (arguments.length === 0) {
                return indexOf(choices.filter(".select2-highlighted")[0], choices.get());
            }

            if (index >= choices.length) index = choices.length - 1;
            if (index < 0) index = 0;

            this.results.find(".select2-highlighted").removeClass("select2-highlighted");

            choice = $(choices[index]);
            choice.addClass("select2-highlighted");

            this.ensureHighlightVisible();

            data = choice.data("select2-data");
            if (data) {
                this.opts.element.trigger({ type: "select2-highlight", val: this.id(data), choice: data });
            }
        }
abstract