static weekdaysFormat(
    length = "long",
    { locale = null, numberingSystem = null, locObj = null } = {}
  ) {
    return (locObj || Locale.create(locale, numberingSystem, null)).weekdays(length, true);
  }
Return an array of format week names.
Format weekdays differ from standalone weekdays in that they're meant to appear next to more date information. In some languages, that
changes the string.
See {@link Info#weekdays}
@param {string} [length='long'] - the length of the month representation, such as "narrow", "short", "long".
@param {Object} opts - options
@param {string} [opts.locale=null] - the locale code
@param {string} [opts.numberingSystem=null] - the numbering system
@param {string} [opts.locObj=null] - an existing locale object to use
@return {Array}