Function useDefaultLocale

packages/react-aria/src/i18n/useDefaultLocale.ts:55–85

()

 * Returns the current browser/system language, and updates when it changes.
 */
export function useDefaultLocale(): Locale {
  let isSSR = useIsSSR();
  let [defaultLocale, setDefaultLocale] = useState(currentLocale);

  useEffect(() => {
    if (listeners.size === 0) {
      window.addEventListener('languagechange', updateLocale);
    }

    listeners.add(setDefaultLocale);

    return () => {
      listeners.delete(setDefaultLocale);
      if (listeners.size === 0) {
        window.removeEventListener('languagechange', updateLocale);
      }
    };
  }, []);

  // We cannot determine the browser's language on the server, so default to
  // en-US. This will be updated after hydration on the client to the correct value.
  if (isSSR) {
    let locale = typeof window !== 'undefined' && window[localeSymbol];
    return {
      locale: locale || 'en-US',
      direction: 'ltr'
    };
  }

  return defaultLocale;
}