Weeks In Year (ISO)

Gets the number of weeks in the current year, according to ISO weeks.

TIP

This requires the IsoWeeksInYear plugin to work

dayjs.extend(isoWeeksInYear);
dayjs.extend(isLeapYear);

dayjs('2004-01-01').isoWeeksInYear(); // 53
dayjs('2005-01-01').isoWeeksInYear(); // 52