Getting Started Internationalising (i18n) with Intlayer and Vite and Solid

Table of Contents

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What is Intlayer?

Intlayer is an innovative, open-source internationalisation (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 localise 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 internationalisation tools for configuration management, translation, content declaration, transpilation, and CLI commands.

• solid-intlayer The package that integrates Intlayer with Solid applications. It provides context providers and hooks for Solid internationalisation.

• 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 localised 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 into Your Vite Configuration

Add the intlayer plugin to your configuration.

import { defineConfig } from "vite";
import react from "@vitejs/plugin-react-swc";
import { intlayer } from "vite-intlayer";

// https://vitejs.dev/config/
export default defineConfig({
  plugins: [react(), 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 optimise 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: {},
} satisfies Dictionary;

export default appContent;

Your content declarations can be defined anywhere in your application as soon as they are included in 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: Utilise 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 an accessor function (e.g., `content.). You must call this function to access the reactive content.

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 localised 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 localised 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 Localised 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()} />;};

(Optional) Step 11: Render Markdown

Intlayer supports rendering Markdown content directly in your Solid application using its own internal parser. By default, Markdown is treated as plain text. To render it as rich HTML, wrap your application with the MarkdownProvider.

import { render } from "solid-js/web";import { MarkdownProvider } from "solid-intlayer/markdown";import App from "./App";const root = document.getElementById("root");render(  () => (    <MarkdownProvider>      <App />    </MarkdownProvider>  ),  root!);

Then you can use it in your components:

import { useIntlayer } from "solid-intlayer";const MyComponent = () => {  const content = useIntlayer("my-content");  return (    <div>      {/* Renders as HTML via MarkdownProvider */}      {content.markdownContent}    </div>  );};

(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

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 externalise your content using the CMS.