Function formatRelative

pkgs/core/src/formatRelative/index.ts:57–101

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

 * //=> "last Thursday at 12:45 AM"
 */
export function formatRelative(
  date: DateArg<Date> & {},
  baseDate: DateArg<Date> & {},
  options?: FormatRelativeOptions,
): string {
  const [date_, baseDate_] = normalizeDates(options?.in, date, baseDate);

  const defaultOptions = getDefaultOptions();
  const locale = options?.locale ?? defaultOptions.locale ?? defaultLocale;
  const weekStartsOn =
    options?.weekStartsOn ??
    options?.locale?.options?.weekStartsOn ??
    defaultOptions.weekStartsOn ??
    defaultOptions.locale?.options?.weekStartsOn ??
    0;

  const diff = differenceInCalendarDays(date_, baseDate_);

  if (isNaN(diff)) {
    throw new RangeError("Invalid time value");
  }

  let token: FormatRelativeToken;
  if (diff < -6) {
    token = "other";
  } else if (diff < -1) {
    token = "lastWeek";
  } else if (diff < 0) {
    token = "yesterday";
  } else if (diff < 1) {
    token = "today";
  } else if (diff < 2) {
    token = "tomorrow";
  } else if (diff < 7) {
    token = "nextWeek";
  } else {
    token = "other";
  }

  const formatStr = locale.formatRelative(token, date_, baseDate_, {
    locale,
    weekStartsOn,
  });
  return format(date_, formatStr, { locale, weekStartsOn });
}