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https://github.com/vinissimus/next-translate
Next.js plugin + i18n API for Next.js 🌍 - Load page translations and use them in an easy way!
https://github.com/vinissimus/next-translate
globalization hacktoberfest i18n localization nextjs plurals preact react static-site tiny trans-component treeshaking usetranslation
Last synced: 2 months ago
JSON representation
Next.js plugin + i18n API for Next.js 🌍 - Load page translations and use them in an easy way!
- Host: GitHub
- URL: https://github.com/vinissimus/next-translate
- Owner: aralroca
- License: mit
- Created: 2019-12-03T08:33:18.000Z (almost 5 years ago)
- Default Branch: master
- Last Pushed: 2024-04-29T21:52:30.000Z (6 months ago)
- Last Synced: 2024-05-02T06:07:19.473Z (6 months ago)
- Topics: globalization, hacktoberfest, i18n, localization, nextjs, plurals, preact, react, static-site, tiny, trans-component, treeshaking, usetranslation
- Language: JavaScript
- Homepage:
- Size: 4.16 MB
- Stars: 2,536
- Watchers: 15
- Forks: 204
- Open Issues: 123
-
Metadata Files:
- Readme: README.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
Awesome Lists containing this project
- Awesome-NextJs - next-translate - `Next.js plugin + i18n API for Next.js earth_africa - Load page translations and use them in an easy way!` (Nextjs Plugins)
- awesome-libraries - next-translate
README
Easy i18n for Next.js +10
Next plugin + i18n API
[](https://badge.fury.io/js/next-translate)
[](https://bundlephobia.com/package/next-translate)
[![PRs Welcome][badge-prwelcome]][prwelcome]
- [1. About next-translate](#1-about-next-translate)
- [How are translations loaded?](#how-are-translations-loaded)
- [2. Getting started](#2-getting-started)
- [Install](#install)
- [Add next-translate plugin](#add-next-translate-plugin)
- [Add i18n.js config file](#add-i18njs-config-file)
- [Create your namespaces files](#create-your-namespaces-files)
- [Use translations in your pages](#use-translations-in-your-pages)
- [3. Configuration](#3-configuration)
- [4. API](#4-api)
- [useTranslation](#usetranslation)
- [createTranslation](#createtranslation)
- [withTranslation](#withtranslation)
- [Trans Component](#trans-component)
- [DynamicNamespaces](#dynamicnamespaces)
- [getT](#gett)
- [I18nProvider](#i18nprovider)
- [appWithI18n](#appwithi18n)
- [loadNamespaces](#loadnamespaces)
- [5. Plurals](#5-plurals)
- [6. Use HTML inside the translation](#6-use-html-inside-the-translation)
- [7. Nested translations](#7-nested-translations)
- [8. Fallbacks](#8-fallbacks)
- [9. Formatter](#9-formatter)
- [10. How to change the language](#10-how-to-change-the-language)
- [11. How to save the user-defined language](#11-how-to-save-the-user-defined-language)
- [12. How to use multi-language in a page](#12-how-to-use-multi-language-in-a-page)
- [13. How to use next-translate in a mono-repo](#13-how-to-use-next-translate-in-a-mono-repo)
- [14. Use Next 13 app directory](#14-use-next-13-app-directory)
- [15. Demos](#15-demos)
- [Demo from Next.js](#demo-from-nextjs)
- [Basic demo](#basic-demo)
- [Complex demo](#complex-demo)
- [With app directory demo](#with-app-directory-demo)
- [Without the webpack loader demo](#without-the-webpack-loader-demo)
- [Contributors ✨](#contributors-)
## 1. About next-translate
The main goal of this library is to keep the translations as simple as possible in a Next.js environment.
Next-translate has two parts: **Next.js plugin** + **i18n API**.
**Features** ✨
- 🚀 ・ Automatic page optimization (pages dir).
- 🏝️ ・ React 18 server/client pages/components (app dir).
- 🦄 ・ Easy to use and configure.
- 🌍 ・ Basic i18n support: interpolation, plurals, useTranslation hook, Trans component...
- 🈂️ ・ It loads only the necessary translations _(for page and for locale)_.
- 📦 ・ Tiny (~1kb) and tree shakable. No dependencies.
### How are translations loaded?
In the configuration file, you specify each page that namespaces needs:
**i18n.json**
```js
{
"pages": {
"*": ["common"],
"/": ["home"],
"/cart": ["cart"],
"/content/[slug]": ["content"],
"rgx:^/account": ["account"]
}
// rest of config here...
}
```
_[Read here](#create-your-namespaces-files) about how to add the namespaces JSON files._
Next-translate ensures that each page only has its namespaces with the current language. So if we have 100 locales, only 1 will be loaded.
In order to do this we use a **webpack loader** that loads the necessary translation files inside the Next.js methods (**getStaticProps**, **getServerSideProps** or **getInitialProps**). If you have one of these methods already on your page, the webpack loader will use your own method, but the defaults it will use are:
- **`getStaticProps`**. This is the **default method used on most pages**, unless it is a page specified in the next two points. This is for performance, so the calculations are done in build time instead of request time.
- **`getServerSideProps`**. This is the **default method for dynamic pages** like `[slug].js` or `[...catchall].js`. This is because for these pages it is necessary to define the `getStaticPaths` and there is no knowledge of how the slugs should be for each locale. Likewise, how is it by default, only that you write the getStaticPaths then it will already use the getStaticProps to load the translations.
- **`getInitialProps`**. This is the **default method for these pages that use a HoC**. This is in order to avoid conflicts because HoC could overwrite a `getInitialProps`.
This **whole process is transparent**, so in your pages you can directly consume the `useTranslation` hook to use the namespaces, and you don't need to do anything else.
If for some reason you use a `getInitialProps` in your `_app.js` file, then the translations will only be loaded into your `getInitialProps` from `_app.js`. We recommend that for optimization reasons you don't use this approach unless it is absolutely necessary.
## 2. Getting started
### Install
- `yarn add next-translate`
### Add next-translate plugin
The `next-translate-plugin` is a tool that allows developers to efficiently handle translations on a page-by-page basis during the build process. It is distinct from the `next-translate` package, which allows developers to access the translations in the code where it is needed. The plugin works by parsing all pages, searching for the translations and rewriting the page file adding the translations to it. This makes the plugin a more efficient and flexible solution for handling translations within a Next.js application. It is recommended to install the plugin as a devDependency.
- `yarn add next-translate-plugin -D`
In your **next.config.js** file:
```js
const nextTranslate = require('next-translate-plugin')
module.exports = nextTranslate()
```
Or if you already have **next.config.js** file and want to keep the changes in it, pass the config object to the `nextTranslate()`. For example for webpack you could do it like this:
```js
const nextTranslate = require('next-translate-plugin')
module.exports = nextTranslate({
webpack: (config, { isServer, webpack }) => {
return config;
}
})
```
### Add i18n.js config file
Add a configuration file `i18n.json` _(or `i18n.js` with `module.exports`)_ in the root of the project. Each page should have its namespaces. Take a look at it in the [config](#3-configuration) section for more details.
```json
{
"locales": ["en", "ca", "es"],
"defaultLocale": "en",
"pages": {
"*": ["common"],
"/": ["home", "example"],
"/about": ["about"]
}
}
```
In the configuration file you can use both the configuration that we [specified here](#3-configuration) and the own [features about internationalization of Next.js 10](https://nextjs.org/docs/advanced-features/i18n-routing).
### Create your namespaces files
By default the namespaces are specified on the **/locales** root directory in this way:
**/locales**
```bash
.
├── ca
│ ├── common.json
│ └── home.json
├── en
│ ├── common.json
│ └── home.json
└── es
├── common.json
└── home.json
```
Each filename matches the namespace specified on the `pages` config property, while each file content should be similar to this:
```json
{
"title": "Hello world",
"variable-example": "Using a variable {{count}}"
}
```
However, you can use another destination to save your namespaces files using [loadLocaleFrom](#3-configuration) configuration property:
**i18n.js**
```js
{
// ...rest of config
"loadLocaleFrom": (lang, ns) =>
// You can use a dynamic import, fetch, whatever. You should
// return a Promise with the JSON file.
import(`./myTranslationsFiles/${lang}/${ns}.json`).then((m) => m.default),
}
```
### Use translations in your pages
Then, use the translations in the page and its components:
**pages/example.js**
```jsx
import useTranslation from 'next-translate/useTranslation'
export default function ExamplePage() {
const { t, lang } = useTranslation('common')
const example = t('variable-example', { count: 42 })
return
{example} // Using a variable 42
}
```
You can consume the translations directly on your pages, you don't have to worry about loading the namespaces files manually on each page. The [next-translate plugin](#add-next-translate-plugin) loads only the namespaces that the page needs and only with the current language.
## 3. Configuration
In the configuration file you can use both the configuration that we specified here and the own [features about internationalization of Next.js 10](https://nextjs.org/docs/advanced-features/i18n-routing).
| Option | Description | Type | Default |
| ----------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------- | ------------------------------------------------------------------------------- |
| `defaultLocale` | ISO of the default locale ("en" as default). | `string` | `"en"` |
| `locales` | An array with all the languages to use in the project. | `string[]` | `[]` |
| `loadLocaleFrom` | Change the way you load the namespaces. | `function` that returns a `Promise` with the `JSON`. | By default is loading the namespaces from **locales** root directory. |
| `pages` | An object that defines the namespaces used in each page. Example of object: `{"/": ["home", "example"]}`. To add namespaces to all pages you should use the key `"*"`, ex: `{"*": ["common"]}`. It's also possible to use regex using `rgx:` on front: `{"rgx:/form$": ["form"]}`. You can also use a function instead of an array, to provide some namespaces depending on some rules, ex: `{ "/": ({ req, query }) => query.type === 'example' ? ['example'] : []}` | `Object` | `{}` |
| `logger` | Function to log the **missing keys** in development and production. If you are using `i18n.json` as config file you should change it to `i18n.js`. | `function` | By default the logger is a function doing a `console.warn` only in development. | |
| `loggerEnvironment` | String to define if the logger should run in the browser, in node or both | `"node"` | `"browser"` | `"both"` | `"browser"` | |
| `logBuild` | Each page has a log indicating: namespaces, current language and method used to load the namespaces. With this you can disable it. | `Boolean` | `true` |
| `loader` | If you wish to disable the webpack loader and manually load the namespaces on each page, we give you the opportunity to do so by disabling this option. | `Boolean` | `true` |
| `interpolation` | Change the delimiter that is used for interpolation. | `{prefix: string; suffix: string, formatter: function }` | `{prefix: '{{', suffix: '}}'}`
| `keySeparator` | Change the separator that is used for nested keys. Set to `false` to disable keys nesting in JSON translation files. Can be useful if you want to use natural text as keys. | `string` | `false` | `'.'`
| `nsSeparator` | char to split namespace from key. You should set it to `false` if you want to use natural text as keys. | `string` | `false` | `':'`
| `defaultNS` | default namespace used if not passed to `useTranslation` or in the translation key. | `string` | `undefined`
| `staticsHoc` | The HOCs we have in our API ([appWithI18n](#appwithi18n)), do not use [hoist-non-react-statics](https://github.com/mridgway/hoist-non-react-statics) in order not to include more kb than necessary _(static values different than getInitialProps in the pages are rarely used)_. If you have any conflict with statics, you can add hoist-non-react-statics (or any other alternative) here. [See an example](docs/hoist-non-react-statics.md). | `Function` | `null`
| `extensionsRgx` | Change the regex used by the webpack loader to find Next.js pages. | `Regex` | `/\.(tsx\|ts\|js\|mjs\|jsx)$/`
| `revalidate` | If you want to have a default revalidate on each page we give you the opportunity to do so by passing a number to revalidate. You can still define getStaticProps on a page with a different revalidate amount and override this default override. | `Number` | If you don't define it, by default the pages will have no revalidate.
| `pagesInDir` | If you run `next ./my-app` to change where your pages are, you can here define `my-app/pages` so that next-translate can guess where they are. | `String` | If you don't define it, by default the pages will be searched for in the classic places like `pages` and `src/pages`.
| `localesToIgnore` | Indicate these locales to ignore when you are prefixing the default locale using a middleware (in Next +12, [learn how to do it](https://nextjs.org/docs/advanced-features/i18n-routing#prefixing-the-default-locale)) | `Array` | `['default']`
| `allowEmptyStrings` | Change how translated empty strings should be handled. If omitted or passed as true, it returns an empty string. If passed as false, returns the key name itself (including ns). | `Boolean` | `true`
## 4. API
### useTranslation
**Size**: ~150b 📦
This hook is the recommended way to use translations in your pages / components.
- **Input**: string - defaultNamespace (optional)
- **Output**: Object { t: Function, lang: string }
Example:
```jsx
import React from 'react'
import useTranslation from 'next-translate/useTranslation'
export default function Description() {
const { t, lang } = useTranslation('ns1') // default namespace (optional)
const title = t('title')
const titleFromOtherNamespace = t('ns2:title')
const description = t`description` // also works as template string
const example = t('ns2:example', { count: 3 }) // and with query params
const exampleDefault = t('ns:example', { count: 3 }, { default: "The count is: {{count}}." }) // and with default translation
return (
<>
{title}
{description}
{example}
<>
)
}
```
The `t` function:
- **Input**:
- **i18nKey**: string (namespace:key)
- **query**: Object _(optional)_ (example: { name: 'Leonard' })
- **options**: Object _(optional)_
- **fallback**: string | string[] - fallback if i18nKey doesn't exist. [See more](#8-fallbacks).
- **returnObjects**: boolean - Get part of the JSON with all the translations. [See more](#7-nested-translations).
- **default**: string - Default translation for the key. If fallback keys are used, it will be used only after exhausting all the fallbacks.
- **ns**: string - Namespace to use when none is embded in the `i18nKey`.
- **Output**: string
### createTranslation
Similar than `useTranslation` but without being a hook. This helper **only works** in **app dir**.
```ts
const { t, lang } = createTranslation('ns1') // default namespace (optional)
const title = t('title')
```
### withTranslation
**Size**: ~560b 📦
It's an alternative to `useTranslation` hook, but in a HOC for these components that are no-functional. _(Not recommended, it's better to use the `useTranslation` hook.)_.
The `withTranslation` HOC returns a Component with an extra prop named `i18n` (Object { t: Function, lang: string }).
Example:
```jsx
import React from 'react'
import withTranslation from 'next-translate/withTranslation'
class Description extends React.Component {
render() {
const { t, lang } = this.props.i18n
const description = t('common:description')
return
{description}
}
}
export default withTranslation(NoFunctionalComponent)
```
Similar to `useTranslation("common")` you can call `withTranslation` with the second parameter defining a default namespace to use:
```
export default withTranslation(NoFunctionalComponent, "common")
```
### Trans Component
**Size**: ~1.4kb 📦
Sometimes we need to do some translations with HTML inside the text (bolds, links, etc), the `Trans` component is exactly what you need for this. We recommend to use this component only in this case, for other cases we highly recommend the usage of `useTranslation` hook instead.
Example:
```jsx
// The defined dictionary entry is like:
// "example": "<0>The number is <1>{{count}}1>0>",
, ]}
values={{ count: 42 }}
/>
```
Or using `components` prop as a object:
```jsx
// The defined dictionary entry is like:
// "example": "The number is {{count}}",
,
b: ,
}}
values={{ count: 42 }}
defaultTrans="The number is {{count}}"
/>
```
- **Props**:
- `i18nKey` - string - key of i18n entry (namespace:key)
- `components` - Array | Object - In case of Array each index corresponds to the defined tag `<0>`/`<1>`. In case of object each key corresponds to the defined tag ``.
- `values` - Object - query params
- `fallback` - string | string[] - Optional. Fallback i18nKey if the i18nKey doesn't match.
- `defaultTrans` - string - Default translation for the key. If fallback keys are used, it will be used only after exhausting all the fallbacks.
- `ns` - Namespace to use when none is embedded in `i18nKey`
- `returnObjects` - boolean - Get part of the JSON with all the translations. [See more](#7-nested-translations).
In cases where we require the functionality of the `Trans` component, but need a **string** to be interpolated, rather than the output of the `t(props.i18nKey)` function, there is also a `TransText` component, which takes a `text` prop instead of `i18nKey`.
- **Props**:
- `text` - string - The string which (optionally) contains tags requiring interpolation
- `components` - Array | Object - This behaves exactly the same as `Trans` (see above).
This is especially useful when mapping over the output of a `t()` with `returnObjects: true`:
```jsx
// The defined dictionary entry is like:
// "content-list": ["List of things", "with tags"]
const contentList = t('someNamespace:content-list', {}, { returnObjects: true });
{contentList.map((listItem: string) => (
,
em: ,
}}
/>
)}
```
### DynamicNamespaces
**Size**: ~1.5kb 📦
The `DynamicNamespaces` component is useful to load dynamic namespaces, for example, in modals.
Example:
```jsx
import React from 'react'
import Trans from 'next-translate/Trans'
import DynamicNamespaces from 'next-translate/DynamicNamespaces'
export default function ExampleWithDynamicNamespace() {
return (
{/* ALSO IS POSSIBLE TO USE NAMESPACES FROM THE PAGE */}
{/* USING DYNAMIC NAMESPACE */}
)
}
```
Remember that `['dynamic']` namespace should **not** be listed on `pages` configuration:
```js
pages: {
'/my-page': ['common'], // only common namespace
}
```
- **Props**:
- `namespaces` - string[] - list of dynamic namespaces to download - **Required**.
- `fallback`- ReactNode - Fallback to display meanwhile the namespaces are loading. - **Optional**.
- `dynamic` - function - By default it uses the [loadLocaleFrom](#3-configuration) in the configuration to load the namespaces, but you can specify another destination. - **Optional**.
### getT
**Size**: ~1.3kb 📦
Asynchronous function to load the `t` function outside components / pages. It works on both server-side and client-side.
Unlike the useTranslation hook, we can use here any namespace, it doesn't have to be a namespace defined in the "pages" configuration. It downloads the namespace indicated as a parameter on runtime.
You can load multiple namespaces by giving an array as a parameter, in this case the default namespace will be the fist one.
Example inside `getStaticProps`:
```js
import getT from 'next-translate/getT'
// ...
export async function getStaticProps({ locale }) {
const t = await getT(locale, 'common')
const title = t('title')
return { props: { title } }
}
```
Example inside API Route:
```js
import getT from 'next-translate/getT'
export default async function handler(req, res) {
const t = await getT(req.query.__nextLocale, 'common')
const title = t('title')
res.statusCode = 200
res.setHeader('Content-Type', 'application/json')
res.end(JSON.stringify({ title }))
}
```
Example of loading multiple namespaces:
```js
import getT from 'next-translate/getT'
export default async function handler(req, res) {
const t = await getT(req.query.__nextLocale, ['common', 'errors'])
const title = t('title') // The default namespace is the first one.
const errorMessage = t('errors:app_error') // The default namespace is the first one.
res.statusCode = 200
res.setHeader('Content-Type', 'application/json')
res.end(JSON.stringify({ title }))
}
```
### I18nProvider
**Size**: ~3kb 📦
The `I18nProvider` is a context provider internally used by next-translate to provide the current **lang** and the page **namespaces**. **SO MAYBE YOU'LL NEVER NEED THIS**.
However, it's exposed to the API because it can be useful in some cases. For example, to use multi-language translations in a page.
The `I18nProvider` is accumulating the namespaces, so you can rename the new ones in order to keep the old ones.
```jsx
import React from 'react'
import I18nProvider from 'next-translate/I18nProvider'
import useTranslation from 'next-translate/useTranslation'
// Import English common.json
import commonEN from '../../locales/en/common.json'
function PageContent() {
const { t, lang } = useTranslation()
console.log(lang) // -> current language
return (
{t('common:example') /* Current language */}
{t('commonEN:example') /* Force English */}
)
}
export default function Page() {
const { lang } = useTranslation()
return (
)
}
```
### appWithI18n
**Size**: ~3.7kb 📦
The `appWithI18n` is internally used by next-translate. **SO MAYBE YOU'LL NEVER NEED THIS**. However, we expose it in the API in case you disable the webpack [loader](#3-configuration) option and decide to load the namespaces manually.
If you wish not to use the webpack loader, then you should put this in your `_app.js` file (and create the `_app.js` file if you don't have it).
Example:
`_app.js`
```jsx
import appWithI18n from 'next-translate/appWithI18n'
import i18nConfig from '../i18n'
function MyApp({ Component, pageProps }) {
return
}
// Wrapping your _app.js
export default appWithI18n(MyApp, {
...i18nConfig,
// Set to false if you want to load all the namespaces on _app.js getInitialProps
skipInitialProps: true,
})
```
If `skipInitialProps=true`, then you should also use the [loadNamespaces](#loadnamespaces) helper to manually load the namespaces on each page.
### loadNamespaces
**Size**: ~1.9kb 📦
The `loadNamespaces` is internally used by next-translate. **SO MAYBE YOU'LL NEVER NEED THIS**. However, we expose it in the API in case you disable the webpack [loader](#3-configuration) option and decide to load the namespaces manually.
To load the namespaces, you must return in your pages the props that the helper provides.
```js
import loadNamespaces from 'next-translate/loadNamespaces'
export function getStaticProps({ locale }) {
return {
props: {
...(await loadNamespaces({ locale, pathname: '/about' })),
}
}
}
```
🚨 To work well, it is necessary that your `_app.js` will be wrapped with the [appWithI18n](#appwithi18n). Also, the `loadLocaleFrom` configuration property is **mandatory** to define it.
## 5. Plurals
We support 6 plural forms (taken from [CLDR Plurals](http://cldr.unicode.org/index/cldr-spec/plural-rules) page) by adding to the key this suffix (or nesting it under the key with no `_` prefix):
- `_zero`
- `_one` (singular)
- `_two` (dual)
- `_few` (paucal)
- `_many` (also used for fractions if they have a separate class)
- `_other` (required—general plural form—also used if the language only has a single form)
_See more info about plurals [here](https://unicode-org.github.io/cldr-staging/charts/37/supplemental/language_plural_rules.html#sl)_.
Only the last one, **`_other`**, is required because it’s the only common plural form used in all locales.
All other plural forms depends on locale. For example English has only two: `_one` and `_other` (1 cat vs. 2 cats). Some languages have more, like Russian and Arabic.
In addition, we also support **an exact match** by specifying the number (`_0`, `_999`) and this works for all locales. Here is an example:
Code:
```js
// **Note**: Only works if the name of the variable is {{count}}.
t('cart-message', { count })
```
Namespace:
```js
{
"cart-message_0": "The cart is empty", // when count === 0
"cart-message_one": "The cart has only {{count}} product", // singular
"cart-message_other": "The cart has {{count}} products", // plural
"cart-message_999": "The cart is full", // when count === 999
}
```
or
```js
{
"cart-message": {
"0": "The cart is empty", // when count === 0
"one": "The cart has only {{count}} product", // singular
"other": "The cart has {{count}} products", // plural
"999": "The cart is full", // when count === 999
}
}
```
> Intl.PluralRules API is **only available for modern browsers**, if you want to use it in legacy browsers you should add a [polyfill](https://github.com/eemeli/intl-pluralrules).
## 6. Use HTML inside the translation
You can define HTML inside the translation this way:
```json
{
"example-with-html": "<0>This is an example <1>using HTML1> inside the translation0>"
}
```
Example:
```jsx
import Trans from 'next-translate/Trans'
// ...
const Component = (props) =>
// ...
, ]}
/>
```
Rendered result:
```html
This is an example using HTML inside the translation
```
Each index of `components` array corresponds with `` of the definition.
In the `components` array, it's not necessary to pass the children of each element. Children will be calculated.
## 7. Nested translations
In the namespace, it's possible to define nested keys like this:
```json
{
"nested-example": {
"very-nested": {
"nested": "Nested example!"
}
}
}
```
In order to use it, you should use "." as id separator:
```js
t`namespace:nested-example.very-nested.nested`
```
Also is possible to use as array:
```json
{
"array-example": [
{ "example": "Example {{count}}" },
{ "another-example": "Another example {{count}}" }
]
}
```
And get all the array translations with the option `returnObjects`:
```js
t('namespace:array-example', { count: 1 }, { returnObjects: true })
/*
[
{ "example": "Example 1" },
{ "another-example": "Another example 1" }
]
*/
```
Also it is possible to get all the translations by using the keySeparator as the key, default is `'.'` :
```js
t('namespace:.', { count: 1 }, { returnObjects: true })
/*
{
"array-example": [
{ "example": "Example 1" },
{ "another-example": "Another example 1" }
]
}
*/
```
### 8. Fallbacks
If no translation exists you can define fallbacks (`string|string[]`) to search for other translations:
```js
const { t } = useTranslation()
const textOrFallback = t(
'ns:text',
{ count: 1 },
{
fallback: 'ns:fallback',
}
)
```
List of fallbacks:
```js
const { t } = useTranslation()
const textOrFallback = t(
'ns:text',
{ count: 42 },
{
fallback: ['ns:fallback1', 'ns:fallback2'],
}
)
```
In Trans Component:
```jsx
, ]}
values={{ count: 42 }}
fallback={['ns:fallback1', 'ns:fallback2']} // or string with just 1 fallback
/>
```
## 9. Formatter
You can format params using the `interpolation.format` config function.
in `i18n.js`:
```js
const formatters = {
es: new Intl.NumberFormat("es-ES"),
en: new Intl.NumberFormat("en-EN"),
}
return {
// ...
interpolation: {
format: (value, format, lang) => {
if(format === 'number') return formatters[lang].format(value)
return value
}
}
}
```
In English namespace:
```json
{
"example": "The number is {{count, number}}"
}
```
In Spanish namespace:
```json
{
"example": "El número es {{count, number}}"
}
```
Using:
```js
t('example', { count: 33.5 })
```
Returns:
- In English: `The number is 33.5`
- In Spanish: `El número es 33,5`
## 10. How to change the language
In order to change the current language you can use the [Next.js navigation](https://nextjs.org/docs/advanced-features/i18n-routing) (Link and Router) passing the `locale` prop.
An example of a possible `ChangeLanguage` component using the `useRouter` hook from `Next.js`:
```js
import React from 'react'
import Link from 'next/link'
import useTranslation from 'next-translate/useTranslation'
import i18nConfig from '../i18n.json'
const { locales } = i18nConfig
export default function ChangeLanguage() {
const { t, lang } = useTranslation()
return locales.map((lng) => {
if (lng === lang) return null
return (
{t(`layout:language-name-${lng}`)}
)
})
}
```
You could also use `setLanguage` to change the language while keeping the same page.
```js
import React from 'react'
import setLanguage from 'next-translate/setLanguage'
export default function ChangeLanguage() {
return (
await setLanguage('en')}>EN
)
}
```
Another way of accessing the `locales` list to change the language is using the `Next.js router`. The `locales` list can be accessed using the [Next.js useRouter hook](https://nextjs.org/docs/api-reference/next/router#userouter).
## 11. How to save the user-defined language
You can set a cookie named `NEXT_LOCALE` with the user-defined language as value, this way a locale can be forced.
Example of hook:
```js
import { useRouter } from 'next/router'
// ...
function usePersistLocaleCookie() {
const { locale, defaultLocale } = useRouter()
useEffect(persistLocaleCookie, [locale, defaultLocale])
function persistLocaleCookie() {
if(locale !== defaultLocale) {
const date = new Date()
const expireMs = 100 * 24 * 60 * 60 * 1000 // 100 days
date.setTime(date.getTime() + expireMs)
document.cookie = `NEXT_LOCALE=${locale};expires=${date.toUTCString()};path=/`
}
}
}
```
## 12. How to use multi-language in a page
In some cases, when the page is in the current language, you may want to do some exceptions displaying some text in another language.
In this case, you can achieve this by using the `I18nProvider`.
Learn how to do it [here](#i18nprovider).
## 13. How to use next-translate in a mono-repo
Next-translate uses by default the current working directory of the Node.js process (`process.cwd()`).
If you want to change it you can use :
- the `NEXT_TRANSLATE_PATH` environment variable. It supports both relative and absolute path
- the native NodeJS function `process.chdir(PATH_TO_NEXT_TRANSLATE)` to move the `process.cwd()`
## 14. Use Next 13 app directory
When it comes to server components and client components, it can be challenging to load the same thing on different pages. To simplify this process, we have **extracted all the complexity** using the **[`next-translate-plugin`](https://github.com/aralroca/next-translate-plugin)**.
If you're interested in learning more about how Next-translate works with the new Next.js 13 app dir paradigm, check out **[this article](https://dev.to/aralroca/i18n-translations-in-nextjs-13s-app-dir-for-serverclient-components-4ek8)** for a detailed explanation.
### Regarding translations:
If you use the "app" folder instead of the "pages" folder, the `next-translate-plugin` will automatically detect the change, and you won't need to touch any of the Next-translate configuration. The only difference is that the "pages" configuration property will reference the pages located within the "app" folder.
**i18n.js**
```js
module.exports = {
locales: ['en', 'ca', 'es'],
defaultLocale: 'en',
pages: {
'*': ['common'],
'/': ['home'], // app/page.tsx
'/second-page': ['home'], // app/second-page/page.tsx
},
}
```
By simply changing the "pages" folder to "app," you can consume translations within your pages using the **`useTranslation`** hook or the **`Trans`** component. You will still see the log (if enabled) to know which namespaces are loaded on each page, and everything else should be the same.
**🌊 Server page/component (+0kb): `app/page.js`:**
```js
import useTranslation from 'next-translate/useTranslation'
export default function HomePage() {
const { t, lang } = useTranslation('home')
return
{t('title')}
}
```
**🏝️ Client page/component (+498B): `app/checkout/page.js`**
```js
"use client"
import useTranslation from 'next-translate/useTranslation'
export default function CheckoutPage() {
const { t, lang } = useTranslation('checkout')
return
{t('title')}
}
```
### Regarding routing:
Next.js 10 introduced [i18n routing](https://nextjs.org/docs/advanced-features/i18n-routing) support, allowing pages to be rendered by navigating to `/es/page-name`, where the page `pages/page-name.js` was accessed using the `useRouter` hook to obtain the `locale`.
However, since the pages have been moved from the `pages` dir to the **app dir**, this i18n routing **no longer works correctly**.
At Next-translate, we have chosen not to re-implement this functionality, as we aim to be a library for translating pages, rather than routing them. We hope that in the future, this feature will be implemented in the `app` directory.
**We recommend the following:**
- Add the dynamic path `[lang]` to the first level. That is, all your pages will be inside `/app/[lang]`.
- If you need more control over which languages to support, or to detect the browser language, use the [middleware](https://nextjs.org/docs/app/building-your-application/routing/internationalization#routing-overview) that the Next.js team [recommends here](https://nextjs.org/docs/app/building-your-application/routing/internationalization#routing-overview).
- Update all the pages inside `i18n.(js|json)` file to contain the `/[lang]` at the beginning.
```diff
module.exports = {
locales: ['en', 'ca', 'es'],
defaultLocale: 'en',
pages: {
'*': ['common'],
- '/': ['home'],
+ '/[lang]': ['home'],
- '/second-page': ['home'],
+ '/[lang]/second-page': ['home'],
},
}
```
At Next-translate level we **already detect the language automatically** according to `searchParams.get('lang')` and `params.lang`. So you **don't need to configure it for each page**, you can use `next-translate` as **normal** within the server/client pages/components:
```js
import useTranslation from 'next-translate/useTranslation'
import Trans from 'next-translate/Trans'
export default function Page() {
const { t, lang } = useTranslation('common')
return (
<>
{t`title`}
]} />
>
)
}
```
## 15. Demos
### Demo from Next.js
There is a demo of `next-translate` on the Next.js repo:
- https://github.com/vercel/next.js/tree/master/examples/with-next-translate
To use it:
```bash
npx create-next-app --example with-next-translate with-next-translate-app
# or
yarn create next-app --example with-next-translate with-next-translate-app
```
### Basic demo
This demo is in this repository:
- `git clone [email protected]:aralroca/next-translate.git`
- `cd next-translate`
- `yarn && yarn example:basic`
### Complex demo
Similar than the basic demo but with some extras: TypeScript, Webpack 5, MDX, with _app.js on top, pages located on src/pages folder, loading locales from src/translations with a different structure.
This demo is in this repository:
- `git clone [email protected]:aralroca/next-translate.git`
- `cd next-translate`
- `yarn && yarn example:complex`
### With app directory demo
Similar than the complex demo but with some extra: Instead of `pages` folder, we are using the Next.js +13 [app folder with the new layouts system](https://nextjs.org/blog/next-13#new-app-directory-beta).
This demo is in this repository:
- `git clone [email protected]:aralroca/next-translate.git`
- `cd next-translate`
- `yarn && yarn example:with-app-directory`
### Without the webpack loader demo
Similar than the basic example but loading the page namespaces manually deactivating the webpack loader in the i18n.json config file.
> We do not recommend that it be used in this way. However we give the opportunity for anyone to do so if they are not comfortable with our webpack loader.
This demo is in this repository:
- `git clone [email protected]:aralroca/next-translate.git`
- `cd next-translate`
- `yarn && yarn example:without-loader`
[badge-prwelcome]: https://img.shields.io/badge/PRs-welcome-brightgreen.svg?style=flat-square
[prwelcome]: http://makeapullrequest.com
[spectrum]: https://spectrum.chat/next-translate
## Contributors ✨
Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/docs/en/emoji-key)):
Aral Roca Gomez
🚧 💻
Vincent Ducorps
💻
Björn Rave
💻
Justin
💻
Pol
🚇
Ademílson F. Tonato
💻
Faul
💻
bickmaev5
💻
Pierre Grimaud
📖
Roman Minchyn
📖 💻
Egor
💻
Darren
💻
Giovanni Giordano
💻
Eugene
💻
Andrew Chung
💻
Thanh Minh
💻
crouton
💻
Patrick
📖
Vantroy
💻
Joey
💻
gurkerl83
💻
Teemu Perämäki
📖
Luis Serrano
📖
j-schumann
💻
Andre Hsu
💻
slevy85
💻
Bernd Artmüller
💻
Rihards Ščeredins
💻
n4n5
📖
Rubén Moya
💻
Tom Esterez
💻
Dan Needham
💻 ⚠️ 📖
Bruno Antunes
💻
Kaan Atakan
💻
Romain
💻
Arnau Jiménez
💻
Edwin Veldhuizen
💻
Duc Ngo Viet
💻
Billel Helali
💻
Wuif
💻
Michał Bar
💻
Wuif
💻
Marces Engel
💻
Michał Bar
💻
Dragate
💻
Marces Engel
💻
Vasco Silva
💻
Vsevolod Volkov
💻
Felix Yan
📖
Muhammad Al Ziqri
💻
Marcelo Oliveira
💻
Zack Sunderland
💻
Andrew Ovens
💻
dANi
💻
Mateusz Lesiak
💻
Curetix
📖
Honza
🚧
HardikBandhiya
📖
Tim O. Peters
💻
Li Ming
📖
Fernando García Hernández
💻
Hichem Fantar
💻
Huseyin Onal
💻
Jesse Martin
💻
This project follows the [all-contributors](https://github.com/all-contributors/all-contributors) specification. Contributions of any kind welcome!