Function lastDayOfISOWeekYear

pkgs/core/src/lastDayOfISOWeekYear/index.ts:38–53

(
  date: DateArg<DateType>,
  options?: LastDayOfISOWeekYearOptions<ResultDate> | undefined,
)

 * //=> Sun Jan 01 2006 00:00:00
 */
export function lastDayOfISOWeekYear<
  DateType extends Date,
  ResultDate extends Date = DateType,
>(
  date: DateArg<DateType>,
  options?: LastDayOfISOWeekYearOptions<ResultDate> | undefined,
): ResultDate {
  const year = getISOWeekYear(date, options);
  const fourthOfJanuary = constructFrom(options?.in || date, 0);
  fourthOfJanuary.setFullYear(year + 1, 0, 4);
  fourthOfJanuary.setHours(0, 0, 0, 0);

  const date_ = startOfISOWeek(fourthOfJanuary, options);
  date_.setDate(date_.getDate() - 1);
  return date_;
}