Function isSameMonth

packages/@internationalized/date/src/queries.ts:28–34

(a: DateValue, b: DateValue)

 * date.
 */
export function isSameMonth(a: DateValue, b: DateValue): boolean {
  b = toCalendar(b, a.calendar);
  // In the Japanese calendar, months can span multiple eras/years, so only compare the first of the month.
  a = startOfMonth(a);
  b = startOfMonth(b);
  return a.era === b.era && a.year === b.year && a.month === b.month;
}

/**
 * Returns whether the given dates occur in the same year, using the calendar system of the first