Week numbers in calendar

[sinnbeck]

It would be nice if it was possible to show week numbers in calendars.

[reidbarber]

There isn't a built-in way to render this, but you could probably use a custom utility though:

For returning the week of the year:

function getWeekNumber(date: CalendarDate, locale: string): number {
  const startOfYear = new CalendarDate(date.calendar, date.year, 1, 1);
  const dayOfWeek = getDayOfWeek(startOfYear, locale);
  const firstThursday = startOfYear.add({days: (11 - dayOfWeek) % 7});
  
  const weekStart = startOfWeek(date, locale);
  const daysDiff = weekStart.compare(startOfWeek(firstThursday, locale));
  
  return Math.floor(daysDiff / 7) + 1;
}

For returning the week of the month:

function getWeekNumber(date: CalendarDate, locale: string): number {
  const startOfMonth = new CalendarDate(date.calendar, date.year, date.month, 1);
  const monthWeekStart = startOfWeek(startOfMonth, locale);
  const dateWeekStart = startOfWeek(date, locale);
  
  const daysDiff = dateWeekStart.compare(monthWeekStart);
  
  return Math.floor(daysDiff / 7) + 1;
}