getDecade
import { getDecade } from "https://esm.sh/v135/date-fns@3.6.0/index.d.mts";@example
// Which decade belongs 27 November 1942?
const result = getDecade(new Date(1942, 10, 27))
//=> 1940
function getDecade<DateType extends Date>(date: DateType | number | string): number;