weseek__growi/apps/app/config/next-i18next.config.js

const isDev = process.env.NODE_ENV === 'development';

const path = require('path');

const { AllLang, Lang } = require('@growi/core');
const { isServer } = require('@growi/core/dist/utils');
const I18nextChainedBackend = isDev ? require('i18next-chained-backend').default : undefined;
const I18NextHttpBackend = require('i18next-http-backend').default;
const I18NextLocalStorageBackend = require('i18next-localstorage-backend').default;

const HMRPlugin = isDev ? require('i18next-hmr/plugin').HMRPlugin : undefined;

module.exports = {
  defaultLang: Lang.en_US,
  i18n: {
    defaultLocale: Lang.en_US,
    locales: AllLang,
  },
  defaultNS: 'translation',
  localePath: path.resolve('./public/static/locales'),
  serializeConfig: false,
  // eslint-disable-next-line no-nested-ternary
  use: isDev
    ? isServer()
      ? [new HMRPlugin({ webpack: { server: true } })]
      : [I18nextChainedBackend, new HMRPlugin({ webpack: { client: true } })]
    : [],
  backend: {
    backends: isServer() ? [] : [I18NextLocalStorageBackend, I18NextHttpBackend],
    backendOptions: [
      // options for i18next-localstorage-backend
      { expirationTime: isDev ? 0 : 24 * 60 * 60 * 1000 }, // 1 day in production
      // options for i18next-http-backend
      { loadPath: '/static/locales/{{lng}}/{{ns}}.json' },
    ],
  },
};