feat: modernized web application

nextjs/src/i18n/client.ts

@@ -0,0 +1,22 @@
+'use client';
+
+import i18n from 'i18next';
+import { initReactI18next } from 'react-i18next';
+
+import en from './en.json';
+import ja from './ja.json';
+
+if (!i18n.isInitialized) {
+  i18n.use(initReactI18next).init({
+    fallbackLng: 'ja',
+    resources: {
+      en: { translation: en },
+      ja: { translation: ja },
+    },
+    interpolation: {
+      escapeValue: false,
+    },
+  });
+}
+
+export default i18n;