import { addDays , differenceInCalendarDays , Locale , startOfWeek } from 'date-fns' ; export function getOutsideStartDays ( month , options ? ) { const days = [ ] ; const firstDayOfWeek = startOfWeek ( month , options ) ; const startDiff = differenceInCalendarDays ( month , firstDayOfWeek ) ; for ( let i = 0 ; i < startDiff ; i ++ ) { const newDay = addDays ( firstDayOfWeek , i ) ; days . push ( newDay ) ; } return days ; }