i18next-react-native-async-storage/index.js

This plugin caches your user's language in React Native's Async storage

function requireIfAvailable (path) {
  try {
      return require(path);
  } catch (e) {
      return false;
  }
}

const AsyncStorage = (requireIfAvailable('@react-native-async-storage/async-storage') || requireIfAvailable('@react-native-community/async-storage') || requireIfAvailable('react-native')).AsyncStorage

function callFallbackIfFunc(fallback, callback){
  if(typeof fallback === 'function'){
    return fallback(callback)
  }

  return callback(fallback)
}

module.exports = exports = function(fallback){
  return {
    type: 'languageDetector',
    async: true,
    init: () => {},
    detect: async function(callback){
      try {
        await AsyncStorage.getItem('@i18next-async-storage/user-language')
          .then(language => {
            if(language){
              return callback(language)
            }

            return callFallbackIfFunc(fallback, callback)
          })
      } catch(error){
        callFallbackIfFunc(fallback, callback)
      }

    },
    cacheUserLanguage: async function(language){
      try {
        await AsyncStorage.setItem('@i18next-async-storage/user-language', language)
      } catch(error){

      }
    }
  }
};