Translate your Vite and Solid website using Intlayer | Internationalization (i18n)

Table of Contents

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.

Step-by-Step Guide to Set Up Intlayer in a Vite and Solid Application

Table of Contents

Step 1: Install Dependencies

Install the necessary packages using npm:

npm install intlayer solid-intlayernpm install vite-intlayer --save-devnpx intlayer init

• intlayer

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

• solid-intlayer The package that integrates Intlayer with Solid application. It provides context providers and hooks for Solid 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 { Locales, type IntlayerConfig } from "intlayer";

const config: IntlayerConfig = {
  internationalization: {
    locales: [
      Locales.ENGLISH,
      Locales.FRENCH,
      Locales.SPANISH,
      // Your other locales
    ],
    defaultLocale: Locales.ENGLISH,
  },
};

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: Integrate Intlayer in Your Vite Configuration

Add the intlayer plugin into your configuration.

import { defineConfig } from "vite";
import solid from "vite-plugin-solid";
import { intlayer } from "vite-intlayer";

// https://vitejs.dev/config/
export default defineConfig({
  plugins: [solid(), intlayer()],
});

The intlayer() 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 4: Declare Your Content

Create and manage your content declarations to store translations:

import { t, type Dictionary } from "intlayer";

const appContent = {
  key: "app",
  content: {
    viteLogo: t({
      en: "Vite logo",
      fr: "Logo Vite",
      es: "Logo Vite",
    }),
    solidLogo: t({
      en: "Solid logo",
      fr: "Logo Solid",
      es: "Logo Solid",
    }),
    title: "Vite + Solid",
    count: t({
      en: "count is {{count}}",
      fr: "le compte est {{count}}",
      es: "el recuento es {{count}}",
    }),
    edit: t({
      en: "Edit src/App.tsx and save to test HMR",
      fr: "Éditez src/App.tsx et enregistrez pour tester HMR",
      es: "Edita src/App.tsx y guarda para probar HMR",
    }),
    readTheDocs: t({
      en: "Click on the Vite and Solid logos to learn more",
      fr: "Cliquez sur les logos Vite et Solid pour en savoir plus",
      es: "Haga clic en los logotipos de Vite and Solid para obtener más información",
    }),
  },
} satisfies Dictionary;

export default appContent;

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

For more details, refer to the content declaration documentation.

Step 5: Utilize Intlayer in Your Code

Access your content dictionaries throughout your application:

import { createSignal, type Component } from "solid-js";import solidLogo from "./assets/solid.svg";import viteLogo from "/vite.svg";import "./App.css";import { IntlayerProvider, useIntlayer } from "solid-intlayer";const AppContent: Component = () => {  const [count, setCount] = createSignal(0);  const content = useIntlayer("app");  return (    <>      <div>        <a href="https://vitejs.dev" target="_blank">          <img src={viteLogo} class="logo" alt={content.viteLogo.value} />        </a>        <a href="https://www.solidjs.com/" target="_blank">          <img            src={solidLogo}            class="logo solid"            alt={content.solidLogo.value}          />        </a>      </div>      <h1>{content.title}</h1>      <div class="card">        <button onClick={() => setCount((count) => count + 1)}>          {content.count({ count: count() })}        </button>        <p>{content.edit}</p>      </div>      <p class="read-the-docs">{content.readTheDocs}</p>    </>  );};const App: Component = () => (  <IntlayerProvider>    <AppContent />  </IntlayerProvider>);export default App;

In Solid, useIntlayer returns reactive content (e.g., content). You can access its properties directly.

If you want to use your content in a string attribute, such as alt, title, href, aria-label, etc., you can use the value of the function, like:

html

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<img src="{content.image.src.value}" alt="{content.image.value}" /><img src="{content.image.src.toString()}" alt="{content.image.toString()}" /><img src="{String(content.image.src)}" alt="{String(content.image)}" />

(Optional) Step 6: Change the language of your content

To change the language of your content, you can use the setLocale function provided by the useLocale hook. This function allows you to set the locale of the application and update the content accordingly.

import { type Component, For } from "solid-js";import { Locales } from "intlayer";import { useLocale } from "solid-intlayer";const LocaleSwitcher: Component = () => {  const { locale, setLocale, availableLocales } = useLocale();  return (    <select      value={locale()}      onChange={(e) => setLocale(e.currentTarget.value as Locales)}    >      <For each={availableLocales}>        {(loc) => (          <option value={loc} selected={loc === locale()}>            {loc}          </option>        )}      </For>    </select>  );};

(Optional) Step 7: Add localized Routing to your application

The purpose of this step is to make unique routes for each language. This is useful for SEO and SEO-friendly URLs. Example:

- https://example.com/about- https://example.com/es/about- https://example.com/fr/about

To add localized routing to your application, you can use @solidjs/router.

First, install the necessary dependencies:

npm install @solidjs/router

Then, wrap your application with the Router and define your routes using localeMap:

import { render } from "solid-js/web";import { Router } from "@solidjs/router";import App from "./App";const root = document.getElementById("root");render(  () => (    <Router>      <App />    </Router>  ),  root!);

import { type Component } from "solid-js";import { Route } from "@solidjs/router";import { localeMap } from "intlayer";import { IntlayerProvider } from "solid-intlayer";import Home from "./pages/Home";import About from "./pages/About";const App: Component = () => (  <IntlayerProvider>    {localeMap(({ locale, urlPrefix }) => (      <Route        path={urlPrefix || "/"}        component={(props: any) => (          <IntlayerProvider locale={locale}>{props.children}</IntlayerProvider>        )}      >        <Route path="/" component={Home} />        <Route path="/about" component={About} />      </Route>    ))}  </IntlayerProvider>);export default App;

(Optional) Step 8: Change the URL when the locale changes

To change the URL when the locale changes, you can use the onLocaleChange prop provided by the useLocale hook. You can use the useNavigate and useLocation hooks from @solidjs/router to update the URL path.

import { type Component, For } from "solid-js";import { useLocation, useNavigate } from "@solidjs/router";import { getLocalizedUrl } from "intlayer";import { useLocale } from "solid-intlayer";const LocaleSwitcher: Component = () => {  const location = useLocation();  const navigate = useNavigate();  const { locale, setLocale, availableLocales } = useLocale({    onLocaleChange: (loc) => {      const pathWithLocale = getLocalizedUrl(location.pathname, loc);      navigate(pathWithLocale);    },  });  return (    <select      value={locale()}      onChange={(e) => setLocale(e.currentTarget.value as any)}    >      <For each={availableLocales}>        {(loc) => (          <option value={loc} selected={loc === locale()}>            {loc}          </option>        )}      </For>    </select>  );};

(Optional) Step 9: Switch the HTML Language and Direction Attributes

Update the <html> tag's lang and dir attributes to match the current locale for accessibility and SEO.

import { createEffect, type Component } from "solid-js";import { useLocale } from "solid-intlayer";import { getHTMLTextDir } from "intlayer";const AppContent: Component = () => {  const { locale } = useLocale();  createEffect(() => {    document.documentElement.lang = locale();    document.documentElement.dir = getHTMLTextDir(locale());  });  return (    // ... Your application content  );};

(Optional) Step 10: Creating a Localized Link Component

Create a custom Link component that automatically prefixes internal URLs with the current language.

import { type ParentComponent } from "solid-js";import { A, type AnchorProps } from "@solidjs/router";import { getLocalizedUrl } from "intlayer";import { useLocale } from "solid-intlayer";export const Link: ParentComponent<AnchorProps> = (props) => {  const { locale } = useLocale();  const isExternal = () => props.href.startsWith("http");  const localizedHref = () =>    isExternal() ? props.href : getLocalizedUrl(props.href, locale());  return <A {...props} href={localizedHref()} />;};

In parallel, you can also use the intlayerProxy to add server-side routing to your application. This plugin will automatically detect the current locale based on the URL and set the appropriate locale cookie. If no locale is specified, the plugin will determine the most appropriate locale based on the user's browser language preferences. If no locale is detected, it will redirect to the default locale.

Note that to use the intlayerProxy in production, you need to switch the vite-intlayer package from devDependencies to dependencies.

import { defineConfig } from "vite";import solid from "vite-plugin-solid";import { intlayer, intlayerProxy } from "vite-intlayer";// https://vitejs.dev/config/export default defineConfig({  plugins: [    intlayerProxy(), // should be placed first    solid(),    intlayer(),  ],});

(Optional) Step 11: Extract the content of your components

If you have an existing codebase, transforming thousands of files can be time-consuming.

To ease this process, Intlayer propose a compiler / extractor to transform your components and extract the content.

To set it up, you can add a compiler section in your intlayer.config.ts file:

import { type IntlayerConfig } from "intlayer";

const config: IntlayerConfig = {
  // ... Rest of your config
  compiler: {
    /**
     * Indicates if the compiler should be enabled.
     */
    enabled: true,

    /**
     * Defines the output files path
     */
    output: ({ fileName, extension }) => `./${fileName}${extension}`,

    /**
     * Indicates if the components should be saved after being transformed.
     *
     * - If `true`, the compiler will rewrite the component file in the disk. So the transformation will be permanent, and the compiler will skip the transformation for the next process. That way, the compiler can transform the app, and then it can be removed.
     *
     * - If `false`, the compiler will inject the `useIntlayer()` function call into the code in the build output only, and keep the base codebase intact. The transformation will be done only in memory.
     */
    saveComponents: false,

    /**
     * Dictionary key prefix
     */
    dictionaryKeyPrefix: "",
  },
};

export default config;

npx intlayer extract

import { defineConfig } from "vite";import { intlayer, intlayerCompiler } from "vite-intlayer";export default defineConfig({ plugins: [   intlayer(),   intlayerCompiler(), // Adds the compiler plugin ],});

npm run build # Or npm run dev

(Optional) Sitemap and robots.txt (build-time)

Intlayer includes formatters such as generateSitemap and getMultilingualUrls that produce crawler-ready multilingual sitemap.xml and robots.txt output you can write into your project’s public/ folder. In practice you run a small Node script before Vite (for example predev / prebuild npm hooks) so those files exist when you build or serve the app.

Sitemap

Intlayer’s sitemap generator respects your locale setup and includes the usual metadata for crawlers.

The generated sitemap supports the xhtml:link namespace (hreflang XML extensions). Unlike basic generators that only emit flat URLs, Intlayer wires bidirectional links between every localized variant of each page (for example /about, /fr/about, or /about?lang=fr, depending on your routing mode), which helps search engines relate localized URLs.

Robots.txt

Use getMultilingualUrls so Disallow entries cover every localized spelling of sensitive paths.

1. Add generate-seo.mjs at the project root

import fs from "fs";import path from "path";import { fileURLToPath } from "url";import { generateSitemap, getMultilingualUrls } from "intlayer";const __dirname = path.dirname(fileURLToPath(import.meta.url));const SITE_URL = (process.env.SITE_URL || "http://localhost:5173").replace(  /\/$/,  "");const pathList = [  { path: "/", changefreq: "daily", priority: 1.0 },  { path: "/about", changefreq: "monthly", priority: 0.7 },];const sitemapXml = generateSitemap(pathList, { siteUrl: SITE_URL });fs.writeFileSync(path.join(__dirname, "public", "sitemap.xml"), sitemapXml);const getAllMultilingualUrls = (urls) =>  urls.flatMap((url) => Object.values(getMultilingualUrls(url)));const disallowedPaths = getAllMultilingualUrls(["/admin", "/private"]);const robotsTxt = [  "User-agent: *",  "Allow: /",  ...disallowedPaths.map((path) => `Disallow: ${path}`),  "",  `Sitemap: ${SITE_URL}/sitemap.xml`,].join("\n");fs.writeFileSync(path.join(__dirname, "public", "robots.txt"), robotsTxt);console.log("SEO files generated successfully.");

intlayer must be installed so the script can import it. Set SITE_URL in the environment for production (for example in CI).

Prefer generate-seo.mjs for Node ESM. If you use generate-seo.js instead, ensure "type": "module" is set in package.json, or run Node with ESM enabled.

2. Run the script before Vite

{  "scripts": {    "dev": "vite",    "prebuild": "node generate-seo.mjs",    "build": "vite build",    "preview": "vite preview"  }}

Adjust if you use pnpm or yarn. You can also invoke the same script from CI or another step if that fits your workflow.

Configure TypeScript

Ensure your TypeScript configuration includes the autogenerated types.

{  "compilerOptions": {    // ...  },  "include": ["src", ".intlayer/**/*.ts"],}

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

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

Go Further

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