selectDefaultLanguage.js

const defaultLanguage = () => {
  const languageFromStorage = localStorage.getItem("lang");
  if (languageFromStorage) {
    I18n.setLanguage(languageFromStorage);
    return languageFromStorage;
  } else {
    const detectedLang = navigator.languages
      ? navigator.languages[0]
      : navigator.language || navigator.userLanguage;
    let adaptLang = detectedLang.slice(0, 2);
    if (Object.keys(languages).indexOf(adaptLang) === -1) {
      adaptLang = "en";
    }
    I18n.setLanguage(adaptLang);
    return adaptLang;
  }
};