Set JQqueryUI DatePicker to browser languarge, requires jquery-ui-i18n.js

gistfile1.js

var getJqueryUserLanguage = function() {
  if (navigator.language.toLowerCase() == 'en-us') {
      return '';
  }
  else {
      var l = navigator.language.toLowerCase().split('-');
      if (l.length == 1) {
          if ($.datepicker.regional[l[0]] != undefined) return l[0];
          else return '';
      }
      else if (l.length > 1) {
          if ($.datepicker.regional[l[0] + '-' + l[1].toUpperCase()] != undefined) return l[0] + '-' + l[1].toUpperCase();
          else if ($.datepicker.regional[l[0]] != undefined) return l[0];
          else return '';
      }
      else {
          return '';
      }
  }
}

$.datepicker.setDefaults( $.datepicker.regional[ getJqueryUserLanguage() ] );