import { format, formatDistance, formatRelative, subDays } from 'date-fns' format(new Date(), "'Today is a' iiii") //=> "Today is a Sunday" formatDistance(subDays(new Date(), 3), new Date()) //=> "3 days ago" formatRelative(subDays(new Date(), 3), new Date()) //=> "last Friday at 7:26 p.m." format, formatDistance, formatRelative, subDays などの関数を import してそのまま使うだけですね。 加算 https://date-fns.org/v2.15.0