Function getWeekOfMonth

pkgs/core/src/getWeekOfMonth/index.ts:37–59

(
  date: DateArg<Date> & {},
  options?: GetWeekOfMonthOptions,
)

 * //=> 2
 */
export function getWeekOfMonth(
  date: DateArg<Date> & {},
  options?: GetWeekOfMonthOptions,
): number {
  const defaultOptions = getDefaultOptions();
  const weekStartsOn =
    options?.weekStartsOn ??
    options?.locale?.options?.weekStartsOn ??
    defaultOptions.weekStartsOn ??
    defaultOptions.locale?.options?.weekStartsOn ??
    0;

  const currentDayOfMonth = getDate(toDate(date, options?.in));
  if (isNaN(currentDayOfMonth)) return NaN;

  const startWeekDay = getDay(startOfMonth(date, options));

  let lastDayOfFirstWeek = weekStartsOn - startWeekDay;
  if (lastDayOfFirstWeek <= 0) lastDayOfFirstWeek += 7;

  const remainingDaysAfterFirstWeek = currentDayOfMonth - lastDayOfFirstWeek;
  return Math.ceil(remainingDaysAfterFirstWeek / 7) + 1;
}