Function formatDuration

pkgs/core/src/formatDuration/index.ts:86–114

(
  duration: Duration,
  options?: FormatDurationOptions,
)

 * //=> '2 years, 9 months, 3 weeks'
 */
export function formatDuration(
  duration: Duration,
  options?: FormatDurationOptions,
): string {
  const defaultOptions = getDefaultOptions();
  const locale = options?.locale ?? defaultOptions.locale ?? defaultLocale;
  const format = options?.format ?? defaultFormat;
  const zero = options?.zero ?? false;
  const delimiter = options?.delimiter ?? " ";

  if (!locale.formatDistance) {
    return "";
  }

  const result = format
    .reduce((acc, unit) => {
      const token = `x${unit.replace(/(^.)/, (m) =>
        m.toUpperCase(),
      )}` as FormatDistanceToken;
      const value = duration[unit];
      if (value !== undefined && (zero || duration[unit])) {
        return acc.concat(locale.formatDistance(token, value));
      }
      return acc;
    }, [] as string[])
    .join(delimiter);

  return result;
}