Function formatRange

packages/react-aria/src/calendar/utils.ts:145–178

(
  dateFormatter: DateFormatter,
  stringFormatter: LocalizedStringFormatter,
  start: CalendarDate,
  end: CalendarDate,
  timeZone: string
)

}

function formatRange(
  dateFormatter: DateFormatter,
  stringFormatter: LocalizedStringFormatter,
  start: CalendarDate,
  end: CalendarDate,
  timeZone: string
) {
  let parts = dateFormatter.formatRangeToParts(start.toDate(timeZone), end.toDate(timeZone));

  // Find the separator between the start and end date. This is determined
  // by finding the last shared literal before the end range.
  let separatorIndex = -1;
  for (let i = 0; i < parts.length; i++) {
    let part = parts[i];
    if (part.source === 'shared' && part.type === 'literal') {
      separatorIndex = i;
    } else if (part.source === 'endRange') {
      break;
    }
  }

  // Now we can combine the parts into start and end strings.
  let startValue = '';
  let endValue = '';
  for (let i = 0; i < parts.length; i++) {
    if (i < separatorIndex) {
      startValue += parts[i].value;
    } else if (i > separatorIndex) {
      endValue += parts[i].value;
    }
  }

  return stringFormatter.format('dateRange', {startDate: startValue, endDate: endValue});
}