The files in this directory were downloaded from: https://github.com/jquery/jquery-ui/tree/master/ui/i18n These files were meant to work with the exploded version of jQuery (not the single file), and so the following changes were made: 6c6,8 < define( [ "../widgets/datepicker" ], factory ); --- > define( [ 'jquery', 'jquery-ui' ], function($) { > return factory($.datepicker); > });