lastDayOfDecade
import { lastDayOfDecade } from "https://esm.sh/v135/date-fns@3.6.0/index.d.mts";@example
// The last day of a decade for 21 December 2012 21:12:00:
const result = lastDayOfDecade(new Date(2012, 11, 21, 21, 12, 00))
//=> Wed Dec 31 2019 00:00:00
function lastDayOfDecade<DateType extends Date>(date: DateType | number | string): DateType;