code: function setlocale(locale) {
        locale = typeof(locale) === "undefined" ? "en_US" : locale;
  
        if((cldr && (cldr.localeIds.indexOf(locale.replace(/-/g, '_').toLowerCase()) === -1)) || (!cldr && ((locale.replace(/-/g, '_').toLowerCase() !== "en_us")))) {
           throw new IllegalLocaleError();
        }
  
        this.day_name   = _extractLocaleDays(false, locale);
        this.day_abbr   = _extractLocaleDays(true, locale);
        this.month_name = _extractLocaleMonths(false, locale);
        this.month_abbr = _extractLocaleMonths(true, locale);
      }
docs: Sets the locale for use in extracting month and weekday names.
  
  @param {String} locale
  @throws {IllegalLocaleError} If the provided locale is invalid.
  @api public