next-i18next
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The easiest way to translate your NextJs apps.
132 lines (131 loc) • 4.7 kB
JavaScript
'use client';
"use client";
import { useCallback, useEffect, useState } from "react";
import { createInstance } from "i18next";
import { I18nextProvider, Trans, useTranslation } from "react-i18next";
import { initReactI18next } from "react-i18next/initReactI18next";
import resourcesToBackend from "i18next-resources-to-backend";
import { useParams, useRouter } from "next/navigation";
import { jsx } from "react/jsx-runtime";
//#region src/appRouter/client.tsx
/**
* Client-side i18next provider for App Router.
* Creates an i18next instance hydrated with server-loaded resources,
* with fallback dynamic loading for additional namespaces.
*
* Supports custom backends via the `use` prop — pass i18next-http-backend,
* i18next-locize-backend, or i18next-chained-backend to load translations
* from external sources.
*
* @example
* ```tsx
* // In app/[lng]/layout.tsx (Server Component)
* import { I18nProvider } from 'next-i18next/client'
* import { getT, getResources } from 'next-i18next/server'
*
* export default async function Layout({ children, params }) {
* const { lng } = await params
* const { i18n } = await getT()
* const resources = getResources(i18n, ['common'])
* return (
* <I18nProvider language={lng} resources={resources}>
* {children}
* </I18nProvider>
* )
* }
* ```
*/
function I18nProvider({ children, language, resources, supportedLngs, defaultNS = "common", fallbackLng, localePath = "/locales", localeStructure = "{{lng}}/{{ns}}", localeExtension = "json", use = [], i18nextOptions = {} }) {
const [instance] = useState(() => {
const inst = createInstance();
inst.use(initReactI18next);
const userHasBackend = use.some((b) => b.type === "backend");
const bundledNsSet = resources ? new Set(Object.values(resources).flatMap((r) => Object.keys(r))) : /* @__PURE__ */ new Set();
const bundledNs = bundledNsSet.size > 0 ? [...bundledNsSet] : [defaultNS];
if (!userHasBackend) inst.use(resourcesToBackend((lng, ns) => {
if (bundledNsSet.has(ns)) return {};
const path = `${localePath}/${localeStructure.replace("{{lng}}", lng).replace("{{ns}}", ns)}.${localeExtension}`;
return fetch(path).then((r) => r.ok ? r.json() : {});
}));
use.forEach((plugin) => inst.use(plugin));
const hasAnyBackend = userHasBackend || !resources;
inst.init({
lng: language,
resources,
ns: bundledNs,
partialBundledLanguages: hasAnyBackend,
defaultNS,
fallbackLng: fallbackLng ?? language,
supportedLngs: supportedLngs ?? (resources ? Object.keys(resources) : [language]),
fallbackNS: defaultNS,
interpolation: { escapeValue: false },
react: { useSuspense: false },
...i18nextOptions
});
return inst;
});
useEffect(() => {
if (instance.language !== language) instance.changeLanguage(language);
}, [instance, language]);
return /* @__PURE__ */ jsx(I18nextProvider, {
i18n: instance,
children
});
}
/**
* Translation hook for Client Components in App Router.
* Works in both locale-in-path and no-locale-path modes:
* - Locale-in-path: reads language from URL params (`[lng]` or `[locale]`) and syncs
* - No-locale-path: uses the language set by I18nProvider (from server detection)
*
* @example
* ```tsx
* 'use client'
* import { useT } from 'next-i18next/client'
*
* export default function Counter() {
* const { t } = useT('home')
* return <p>{t('greeting')}</p>
* }
* ```
*/
function useT(ns, options) {
const params = useParams();
const lngFromParams = typeof params?.lng === "string" ? params.lng : typeof params?.locale === "string" ? params.locale : void 0;
const ret = useTranslation(ns, options);
useEffect(() => {
if (lngFromParams && ret.i18n.resolvedLanguage !== lngFromParams) ret.i18n.changeLanguage(lngFromParams);
}, [lngFromParams, ret.i18n]);
return ret;
}
/**
* Hook for changing the language without URL navigation (no-locale-path mode).
* Updates cookie + i18next instance + triggers server re-render via router.refresh().
*
* @example
* ```tsx
* 'use client'
* import { useChangeLanguage } from 'next-i18next/client'
*
* export default function LanguageSwitcher() {
* const changeLanguage = useChangeLanguage()
* return <button onClick={() => changeLanguage('de')}>Deutsch</button>
* }
* ```
*/
function useChangeLanguage(cookieName = "i18next") {
const { i18n } = useTranslation();
const router = useRouter();
return useCallback(async (newLng) => {
document.cookie = `${cookieName}=${newLng};path=/;max-age=${365 * 24 * 60 * 60};SameSite=Lax`;
await i18n.changeLanguage(newLng);
router.refresh();
}, [
i18n,
router,
cookieName
]);
}
//#endregion
export { I18nProvider, Trans, useChangeLanguage, useT };
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