Edit

Accessing locale specific functionality

You can access the properties of the currently loaded locale through the dayjs.localeData() function, or dayjs().localeData() for current Day.js object.

This dependent on LocaleData plugin to work

dayjs.extend(localeData)

globalLocaleData = dayjs.localeData()
globalLocaleData.firstDayOfWeek()
globalLocaleData.months()
globalLocaleData.monthsShort()
globalLocaleData.weekdays()
globalLocaleData.weekdaysShort()
globalLocaleData.weekdaysMin()

globalLocaleData.months(dayjs())
globalLocaleData.monthsShort(dayjs())
globalLocaleData.weekdays(dayjs())
globalLocaleData.weekdaysShort(dayjs())
globalLocaleData.weekdaysMin(dayjs())

instanceLocaleData = dayjs().localeData()
instanceLocaleData.firstDayOfWeek()
instanceLocaleData.months()
instanceLocaleData.monthsShort()
instanceLocaleData.weekdays()
instanceLocaleData.weekdaysShort()
instanceLocaleData.weekdaysMin()