import { lastDayOfDecade } from "https://deno.land/x/date_fns@v2.12.0/index.js";
Examples
// The last day of a decade for 21 December 2012 21:12:00:
var result = lastDayOfDecade(new Date(2012, 11, 21, 21, 12, 00))
//=> Wed Dec 31 2019 00:00:00
// The last day of a decade for 21 December 2012 21:12:00: var result = lastDayOfDecade(new Date(2012, 11, 21, 21, 12, 00)) //=> Wed Dec 31 2019 00:00:00