Getting Started Internationalizing (i18n) with Intlayer and React Router v7

This guide demonstrates how to integrate Intlayer for seamless internationalization in React Router v7 projects with locale-aware routing, TypeScript support, and modern development practices.

What is Intlayer?

Intlayer is an innovative, open-source internationalization (i18n) library designed to simplify multilingual support in modern web applications.

With Intlayer, you can:

• Easily manage translations using declarative dictionaries at the component level.
• Dynamically localize metadata, routes, and content.
• Ensure TypeScript support with autogenerated types, improving autocompletion and error detection.
• Benefit from advanced features, like dynamic locale detection and switching.
• Enable locale-aware routing with React Router v7's configuration-based routing system.

Step-by-Step Guide to Set Up Intlayer in a React Router v7 Application

Step 1: Install Dependencies

Install the necessary packages using your preferred package manager:

npm install intlayer react-intlayernpm install vite-intlayer --save-dev

• intlayer

  The core package that provides internationalization tools for configuration management, translation, content declaration, transpilation, and CLI commands.

• react-intlayer The package that integrates Intlayer with React application. It provides context providers and hooks for React internationalization.

• vite-intlayer Includes the Vite plugin for integrating Intlayer with the Vite bundler, as well as middleware for detecting the user's preferred locale, managing cookies, and handling URL redirection.

Step 2: Configuration of your project

Create a config file to configure the languages of your application:

import { type IntlayerConfig, Locales } from "intlayer";const config: IntlayerConfig = {  internationalization: {    defaultLocale: Locales.ENGLISH,    locales: [Locales.ENGLISH, Locales.TURKISH],  },  middleware: {    prefixDefault: true, // Always prefix default locale in URLs  },};export default config;

Through this configuration file, you can set up localized URLs, middleware redirection, cookie names, the location and extension of your content declarations, disable Intlayer logs in the console, and more. For a complete list of available parameters, refer to the configuration documentation.

Step 3: Configure React Router v7 Routes

Set up your routing configuration with locale-aware routes:

import { layout, route, type RouteConfig } from "@react-router/dev/routes";export default [  layout("routes/layout.tsx", [    route("/", "routes/page.tsx"), // Root page - redirects to locale    route("/:lang", "routes/[lang]/page.tsx"), // Localized home page    route("/:lang/about", "routes/[lang]/about/page.tsx"), // Localized about page  ]),] satisfies RouteConfig;

Step 4: Integrate Intlayer in Your Vite Configuration

Add the intlayer plugin into your configuration:

import { reactRouter } from "@react-router/dev/vite";import { defineConfig } from "vite";import { intLayerMiddlewarePlugin, intlayerPlugin } from "vite-intlayer";import tsconfigPaths from "vite-tsconfig-paths";export default defineConfig({  plugins: [    reactRouter(),    tsconfigPaths(),    intlayerPlugin(),    intLayerMiddlewarePlugin(),  ],});

The intlayerPlugin() Vite plugin is used to integrate Intlayer with Vite. It ensures the building of content declaration files and monitors them in development mode. It defines Intlayer environment variables within the Vite application. Additionally, it provides aliases to optimize performance.

Step 5: Create Layout Components

Set up your root layout and locale-specific layouts:

Root Layout

// app/routes/layout.tsximport { Outlet } from "react-router";import { IntlayerProvider } from "react-intlayer";export default function RootLayout() {  return (    <IntlayerProvider>      <Outlet />    </IntlayerProvider>  );}

Step 6: Declare Your Content

Create and manage your content declarations to store translations:

import { t, type Dictionary } from "intlayer";const pageContent = {  key: "page",  content: {    title: t({      en: "Welcome to React Router v7 + Intlayer",      tr: "React Router v7 + Intlayer'a Hoş Geldiniz",    }),    description: t({      en: "Build multilingual applications with ease using React Router v7 and Intlayer.",      tr: "React Router v7 ve Intlayer kullanarak kolayca çok dilli uygulamalar geliştirin.",    }),    aboutLink: t({      en: "Learn About Us",      tr: "Hakkımızda Öğrenin",    }),    homeLink: t({      en: "Home",      tr: "Ana Sayfa",    }),  },} satisfies Dictionary;export default pageContent;

Your content declarations can be defined anywhere in your application as soon they are included into the contentDir directory (by default, ./app). And match the content declaration file extension (by default, .content.{json,ts,tsx,js,jsx,mjs,mjx,cjs,cjx}).

For more details, refer to the content declaration documentation.

Step 7: Create Locale-Aware Components

Create a LocalizedLink component for locale-aware navigation:

// app/components/localized-link.tsximport { getLocalizedUrl } from "intlayer";import { useLocale } from "react-intlayer";import React from "react";import { Link, useLocation } from "react-router";type RouterLinkProps = React.ComponentProps<typeof Link>;export default function LocalizedLink({ to, ...props }: RouterLinkProps) {  const { locale } = useLocale();  const location = useLocation();  const isExternal = (path: string) =>    /^([a-z][a-z0-9+.-]*:)?\/\//i.test(path) || path.startsWith("mailto:");  if (typeof to === "string") {    if (to.startsWith("/") && !isExternal(to)) {      return <Link to={getLocalizedUrl(to, locale)} {...props} />;    }    return <Link to={to} {...props} />;  }  if (to && typeof to === "object") {    const pathname = (to as { pathname?: string }).pathname;    if (pathname && pathname.startsWith("/") && !isExternal(pathname)) {      return (        <Link          to={{ ...to, pathname: getLocalizedUrl(pathname, locale) }}          {...props}        />      );    }    return <Link to={to} {...props} />;  }  return (    <Link      to={getLocalizedUrl(location.pathname + location.search, locale)}      {...props}    />  );}

Step 8: Utilize Intlayer in Your Pages

Access your content dictionaries throughout your application:

Root Redirect Page

// app/routes/page.tsximport { useLocale } from "react-intlayer";import { Navigate } from "react-router";export default function Page() {  const { locale } = useLocale();  return <Navigate replace to={locale} />;}

Localized Home Page

import { useIntlayer } from "react-intlayer";import LocalizedLink from "~/components/localized-link";export default function Page() {  const content = useIntlayer("page");  return (    <div style={{ padding: "2rem", textAlign: "center" }}>      <h1>{content.title}</h1>      <p>{content.description}</p>      <nav style={{ marginTop: "2rem" }}>        <LocalizedLink          to="/about"          style={{            display: "inline-block",            padding: "0.5rem 1rem",            backgroundColor: "#007bff",            color: "white",            textDecoration: "none",            borderRadius: "4px",          }}        >          {content.aboutLink}        </LocalizedLink>      </nav>    </div>  );}

To Learn more about the useIntlayer hook, refer to the documentation.

Step 9: Create a Locale Switcher Component

Create a component to allow users to change languages:

import { getLocalizedUrl, getLocaleName } from "intlayer";import { useLocale } from "react-intlayer";import { useLocation, useNavigate } from "react-router";export default function LocaleSwitcher() {  const { locale, availableLocales, setLocale } = useLocale();  const location = useLocation();  const navigate = useNavigate();  const handleLocaleChange = (newLocale: string) => {    const localizedUrl = getLocalizedUrl(      location.pathname + location.search,      newLocale    );    setLocale(newLocale);    navigate(localizedUrl);  };  return (    <div style={{ margin: "1rem 0" }}>      <label htmlFor="locale-select">Choose Language: </label>      <select        id="locale-select"        value={locale}        onChange={(e) => handleLocaleChange(e.target.value)}        style={{ padding: "0.25rem", marginLeft: "0.5rem" }}      >        {availableLocales.map((availableLocale) => (          <option key={availableLocale} value={availableLocale}>            {getLocaleName(availableLocale)}          </option>        ))}      </select>    </div>  );}

To Learn more about the useLocale hook, refer to the documentation.

Step 10: Add HTML Attributes Management (Optional)

Create a hook to manage HTML lang and dir attributes:

// app/hooks/useI18nHTMLAttributes.tsximport { getHTMLTextDir } from "intlayer";import { useEffect } from "react";import { useLocale } from "react-intlayer";export const useI18nHTMLAttributes = () => {  const { locale } = useLocale();  useEffect(() => {    document.documentElement.lang = locale;    document.documentElement.dir = getHTMLTextDir(locale);  }, [locale]);};

Then use it in your root component:

// app/routes/layout.tsximport { Outlet } from "react-router";import { IntlayerProvider } from "react-intlayer";import { useI18nHTMLAttributes } from "app/hooks/useI18nHTMLAttributes"; // import the hookexport default function RootLayout() {  useI18nHTMLAttributes(); // call the hook  return (    <IntlayerProvider>      <Outlet />    </IntlayerProvider>  );}

Step 11: Build and Run Your Application

Build the content dictionaries and run your application:

# Build Intlayer dictionariesnpm run intlayer:build# Start development servernpm run dev

Step 12: Configure TypeScript (Optional)

Intlayer uses module augmentation to get benefits of TypeScript and make your codebase stronger.

Ensure your TypeScript configuration includes the autogenerated types:

{  compilerOptions: {    // ... your existing TypeScript configurations  },  include: [    // ... your existing includes    ".intlayer/**/*.ts", // Include the auto-generated types  ],}

Git Configuration

It is recommended to ignore the files generated by Intlayer. This allows you to avoid committing them to your Git repository.

To do this, you can add the following instructions to your .gitignore file:

# Ignore the files generated by Intlayer.intlayer

Production Deployment

When deploying your application:

1. Build your application:

   bash

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   npm run build

2. Build Intlayer dictionaries:

   bash

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   npm run intlayer:build

3. Move vite-intlayer to dependencies if using middleware in production:

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   npm install vite-intlayer --save

Your application will now support:

• URL Structure: /en, /en/about, /tr, /tr/about
• Automatic locale detection based on browser preferences
• Locale-aware routing with React Router v7
• TypeScript support with auto-generated types
• Server-side rendering with proper locale handling

VS Code Extension

To improve your development experience with Intlayer, you can install the official Intlayer VS Code Extension.

Install from the VS Code Marketplace

This extension provides:

• Autocompletion for translation keys.
• Real-time error detection for missing translations.
• Inline previews of translated content.
• Quick actions to easily create and update translations.

For more details on how to use the extension, refer to the Intlayer VS Code Extension documentation.

Go Further

To go further, you can implement the visual editor or externalize your content using the CMS.

Documentation References

• Intlayer Documentation
• React Router v7 Documentation
• useIntlayer hook
• useLocale hook
• Content Declaration
• Configuration

This comprehensive guide provides everything you need to integrate Intlayer with React Router v7 for a fully internationalized application with locale-aware routing and TypeScript support.

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