items.length - 1) { // Down\n      index++\n    }\n\n    if (index < 0) {\n      index = 0\n    }\n\n    items[index].focus()\n  }\n}\n\n/**\n * Data API implementation\n */\n\n$(document)\n  .on(EVENT_KEYDOWN_DATA_API, SELECTOR_DATA_TOGGLE, Dropdown._dataApiKeydownHandler)\n  .on(EVENT_KEYDOWN_DATA_API, SELECTOR_MENU, Dropdown._dataApiKeydownHandler)\n  .on(`${EVENT_CLICK_DATA_API} ${EVENT_KEYUP_DATA_API}`, Dropdown._clearMenus)\n  .on(EVENT_CLICK_DATA_API, SELECTOR_DATA_TOGGLE, function (event)...