next-intlayer/README.md

Simplify internationalization i18n in Next.js with context providers, hooks, locale detection, and multilingual content integration.

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# next-intlayer: Internationalize (i18n) an Next.js application

**Intlayer** is a suite of packages designed specifically for JavaScript developers. It is compatible with frameworks like React, Next.js, and Express.js.

**The `next-intlayer` package** allows you to internationalize your Next.js application. It provides context providers and hooks for Next.js internationalization. Additionally, it includes the Next.js plugin for integrating Intlayer with [Webpack](https://webpack.js.org/) or [Turbopack](https://nextjs.org/docs/app/api-reference/turbopack), as well as middleware for detecting the user's preferred locale, managing cookies, and handling URL redirection.

## Why Internationalize Your Next.js Application?

Internationalizing your Next.js application is essential for serving a global audience effectively. It allows your application to deliver content and messages in the preferred language of each user. This capability enhances user experience and broadens your application's reach by making it more accessible and relevant to people from different linguistic backgrounds.

## Why to integrate Intlayer?

- **JavaScript-Powered Content Management**: Harness the flexibility of JavaScript to define and manage your content efficiently.
- **Type-Safe Environment**: Leverage TypeScript to ensure all your content definitions are precise and error-free.
- **Integrated Content Files**: Keep your translations close to their respective components, enhancing maintainability and clarity.

## Installation

Install the necessary package using your preferred package manager:

```bash packageManager="npm"
npm install next-intlayer
```

```bash packageManager="yarn"
yarn add next-intlayer
```

```bash packageManager="pnpm"
pnpm add next-intlayer
```

## Example of usage

With Intlayer, you can declare your content in a structured way anywhere in your codebase.

By default, Intlayer scans for files with the extension `.content.{json,ts,tsx,js,jsx,mjs,mjx,cjs,cjx}`.

> You can modify the default extension by setting the `contentDir` property in the [configuration file](https://intlayer.org/doc/concept/configuration).

```bash codeFormat="typescript"
.
├── intlayer.config.ts
└── src
    └── components
        ├── ClientComponent
        │   ├── index.content.ts
        │   └── index.tsx
        └── ServerComponent
            ├── index.content.ts
            └── index.tsx
```

### Declare your content

`next-intlayer` is made to work with the [`intlayer` package](https://github.com/aymericzip/intlayer/blob/main/docs/en/packages/intlayer/index.md).`intlayer` is a package that allows you to declare your content anywhere in your code. It converts multilingual content declarations into structured dictionaries that integrate seamlessly into your application.

Here’s an example of content declaration:

```tsx filePath="src/ClientComponent/index.content.ts" codeFormat="typescript"
import { t, type Dictionary } from "intlayer";

const clientComponentContent = {
  key: "client-component",
  content: {
    myTranslatedContent: t({
      en: "Hello World",
      fr: "Bonjour le monde",
      es: "Hola Mundo",
    }),
    numberOfCar: enu({
      "<-1": "Less than minus one car",
      "-1": "Minus one car",
      "0": "No cars",
      "1": "One car",
      ">5": "Some cars",
      ">19": "Many cars",
    }),
  },
} satisfies Dictionary;

export default clientComponentContent;
```

### Utilize Content in Your Code

Once you have declared your content, you can use it in your code. Here's an example of how to use the content in a React component:

```tsx {4,7} fileName="src/components/ClientComponentExample.tsx" codeFormat="typescript"
"use client";

import type { FC } from "react";
import { useIntlayer } from "next-intlayer";

export const ClientComponentExample: FC = () => {
  const { myTranslatedContent } = useIntlayer("client-component"); // Create related content declaration

  return (
    <div>
      <p>{myTranslatedContent}</p>
    </div>
  );
};
```

```jsx {3,6} fileName="src/components/ClientComponentExample.mjx" codeFormat="esm"
"use client";

import { useIntlayer } from "next-intlayer";

const ClientComponentExample = () => {
  const { myTranslatedContent } = useIntlayer("client-component"); // Create related content declaration

  return (
    <div>
      <p>{myTranslatedContent}</p>
    </div>
  );
};
```

```jsx {3,6} fileName="src/components/ClientComponentExample.csx" codeFormat="commonjs"
"use client";

const { useIntlayer } = require("next-intlayer");

const ClientComponentExample = () => {
  const { myTranslatedContent } = useIntlayer("client-component"); // Create related content declaration

  return (
    <div>
      <p>{myTranslatedContent}</p>
    </div>
  );
};
```

## Mastering the internationalization of your Next.js application

Intlayer provides a lot of features to help you internationalize your Next.js application. Here are some of the key features:

- **Internationalization of server components**: Intlayer allows you to internationalize your server components in the same way as your client components. This means that you can use the same content declarations for both client and server components.
- **Middleware for Locale Detection**: Intlayer provides middleware to detect the user's preferred locale. This middleware is used to detect the user's preferred locale and redirect them to the appropriate URL as specified in the [configuration](https://intlayer.org/doc/concept/configuration).
- **Internationalization of metadata**: Intlayer provides a way to internationalize your metadata, such as the title of your page, using the `generateMetadata` function provided by Next.js. You can use the `getTranslation` function to translate your metadata.
- **Internationalization of sitemap.xml and robots.txt**: Intlayer allows you to internationalize your sitemap.xml and robots.txt files. You can use the `getMultilingualUrls` function to generate multilingual URLs for your sitemap.
- **Internationalization of URLs**: Intlayer allows you to internationalize your URLs by using the `getMultilingualUrls` function. This function generates multilingual URLs for your sitemap.

**To learn more about these features, refer to the [Next.js Internationalization (i18n) with Intlayer and Next.js 15 App Router](https://intlayer.org/doc/environment/nextjs) guide.**

## Functions provided by `next-intlayer` package

The `next-intlayer` package also provides some functions to help you to internationalize your application.

- [`t()`](https://intlayer.org/doc/packages/next-intlayer/t)
- [`useIntlayer()`](https://intlayer.org/doc/packages/next-intlayer/useIntlayer)
- [`useDictionary()`](https://intlayer.org/doc/packages/next-intlayer/useDictionary)
- [`useLocale()`](https://intlayer.org/doc/packages/next-intlayer/useLocale)
- [`useIntlayerAsync()`](https://intlayer.org/doc/packages/next-intlayer/useIntlayerAsync)

## Read about Intlayer

- [Intlayer Website](https://intlayer.org)
- [Intlayer Documentation](https://intlayer.org/docs)
- [Intlayer GitHub](https://github.com/aymericzip/intlayer)

- [Ask your questions to our smart documentation](https://intlayer.org/docs/chat)