Function getDayOfWeek

packages/@internationalized/date/src/queries.ts:89–101

(date: DateValue, locale: string, firstDayOfWeek?: DayOfWeek)

 * the first day of the week is Sunday, but in France it is Monday.
 */
export function getDayOfWeek(date: DateValue, locale: string, firstDayOfWeek?: DayOfWeek): number {
  let julian = date.calendar.toJulianDay(date);

  // If julian is negative, then julian % 7 will be negative, so we adjust
  // accordingly.  Julian day 0 is Monday.
  let weekStart = firstDayOfWeek ? DAY_MAP[firstDayOfWeek] : getWeekStart(locale);
  let dayOfWeek = Math.ceil(julian + 1 - weekStart) % 7;
  if (dayOfWeek < 0) {
    dayOfWeek += 7;
  }

  return dayOfWeek;
}

/** Returns the current time in the given time zone. */
export function now(timeZone: string): ZonedDateTime {