@intlify/h3

Internationalization middleware & utilities for h3 (and therefore also for Nitro, which is using h3)

Note

You’re viewing the main branch, which is developing for h3 v2. If you want to check h3 v1, please see the v1 branch

🌟 Features

✅️  Translation: Simple API like vue-i18n

✅  Custom locale detector: You can implement your own locale detector on server-side

✅️️  Useful utilities: support internationalization composables utilities via @intlify/utils

💿 Installation

# Using npm
npm install @intlify/h3

# Using yarn
yarn add @intlify/h3

# Using pnpm
pnpm add @intlify/h3

# Using bun
bun add @intlify/h3

🚀 Usage (h3)

import { createServer } from 'node:http'
import { createApp, createRouter, eventHandler, toNodeListener } from 'h3'
import {
  defineI18nMiddleware,
  detectLocaleFromAcceptLanguageHeader,
  useTranslation
} from '@intlify/h3'

// define middleware with vue-i18n like options
const middleware = defineI18nMiddleware({
  // detect locale with `accept-language` header
  locale: detectLocaleFromAcceptLanguageHeader,
  // resource messages
  messages: {
    en: {
      hello: 'Hello {name}!'
    },
    ja: {
      hello: 'こんにちは、{name}！'
    }
  }
  // something options
  // ...
})

// install middleware with `createApp` option
const app = createApp({ ...middleware })

const router = createRouter()
router.get(
  '/',
  eventHandler(async event => {
    // use `useTranslation` in event handler
    const t = await useTranslation(event)
    return t('hello', { name: 'h3' })
  })
)

app.use(router)
createServer(toNodeListener(app)).listen(3000)

🚀 Usage (Nitro)

For usage with Nitro you need to create a plugin instead, create file plugins/i18n.ts:

import { defineNitroPlugin } from 'nitropack/runtime'
import { defineI18nMiddleware, detectLocaleFromAcceptLanguageHeader } from '@intlify/h3'

export default defineNitroPlugin(nitroApp => {
  const { onRequest, onAfterResponse } = defineI18nMiddleware({
    // detect locale with `accept-language` header
    locale: detectLocaleFromAcceptLanguageHeader,
    // resource messages
    messages: {
      en: {
        hello: 'Hello {name}!'
      },
      ja: {
        hello: 'こんにちは、{name}！'
      }
    }
  })

  nitroApp.hooks.hook('request', onRequest)
  nitroApp.hooks.hook('afterResponse', onAfterResponse)
})

🛠️ Custom locale detection

You can detect locale with your custom logic from current H3Event.

example for detecting locale from url query:

import { defineI18nMiddleware, getQueryLocale } from '@intlify/h3'
import type { H3Event } from 'h3'

// define custom locale detector
const localeDetector = (event: H3Event): string => {
  return getQueryLocale(event).toString()
}

const middleware = defineI18nMiddleware({
  // set your custom locale detector
  locale: localeDetector
  // something options
  // ...
})

You can make that function asynchronous. This is useful when loading resources along with locale detection.

Note

The case which a synchronous function returns a promise is not supported. you need to use async function.

import { defineI18nMiddleware } from '@intlify/h3'
import type { DefineLocaleMessage } from '@intlify/h3'
import type { H3Event } from 'h3'

const loader = (path: string) => import(path).then(m => m.default || m)
const messages: Record<string, () => ReturnType<typeof loader>> = {
  en: () => loader('./locales/en.json'),
  ja: () => loader('./locales/ja.json')
}

// define custom locale detector and lazy loading
const localeDetector = async (
  event: H3Event,
  i18n: CoreContext<string, DefineLocaleMessage>
): Promise<string> => {
  // detect locale
  const locale = getCookieLocale(event).toString()

  // resource lazy loading
  const loader = messages[locale]
  if (loader && !i18n.messages[locale]) {
    const message = await loader()
    i18n.messages[locale] = message
  }

  return locale
}

const middleware = defineI18nMiddleware({
  // set your custom locale detector
  locale: localeDetector
  // something options
  // ...
})

🧩 Type-safe resources

Warning

This is experimental feature (inspired from vue-i18n). We would like to get feedback from you 🙂.

Note

The exeample code is here

You can support the type-safe resources with schema using TypeScript on defineI18nMiddleware options.

Locale messages resource:

export default {
  hello: 'hello, {name}!'
}

your application code:

import { defineI18nMiddleware } from '@intlify/h3'
import { createApp } from 'h3'
import en from './locales/en.ts'

// define resource schema, as 'en' is master resource schema
type ResourceSchema = typeof en

const middleware = defineI18nMiddleware<[ResourceSchema], 'en' | 'ja'>({
  messages: {
    en: { hello: 'Hello, {name}' }
  }
  // something options
  // ...
})

const app = createApp({ ...middleware })
// something your implementation code ...
// ...

Result of type checking with tsc:

npx tsc --noEmit
index.ts:13:3 - error TS2741: Property 'ja' is missing in type '{ en: { hello: string; }; }' but required in type '{ en: ResourceSchema; ja: ResourceSchema; }'.

13   messages: {
     ~~~~~~~~

  ../../node_modules/@intlify/core/node_modules/@intlify/core-base/dist/core-base.d.ts:125:5
    125     messages?: {
            ~~~~~~~~
    The expected type comes from property 'messages' which is declared here on type 'CoreOptions<string, { message: ResourceSchema; datetime: DateTimeFormat; number: NumberFormat; }, { messages: "en"; datetimeFormats: "en"; numberFormats: "en"; } | { ...; }, ... 8 more ..., NumberFormats<...>>'


Found 1 error in index.ts:13

If you are using Visual Studio Code as an editor, you can notice that there is a resource definition omission in the editor with the following error before you run the typescript compilation.

🖌️ Resource keys completion

Warning

This is experimental feature (inspired from vue-i18n). We would like to get feedback from you 🙂.

Note

Resource Keys completion can be used if you are using Visual Studio Code

You can completion resources key on translation function with useTranslation.

resource keys completion has twe ways.

Type parameter for useTranslation

Note

The exeample code is here

You can useTranslation set the type parameter to the resource schema you want to key completion of the translation function.

the part of example:

const router = createRouter()
router.get(
  '/',
  eventHandler(async event => {
    type ResourceSchema = {
      hello: string
    }
    // set resource schema as type parameter
    const t = await useTranslation<ResourceSchema>(event)
    // you can completion when you type `t('`
    return t('hello', { name: 'h3' })
  })
)

global resource schema with declare module '@intlify/h3'

Note

The exeample code is here

You can do resource key completion with the translation function using the typescript declare module.

the part of example:

import en from './locales/en.ts'

// 'en' resource is master schema
type ResourceSchema = typeof en

// you can put the type extending with `declare module` as global resource schema
declare module '@intlify/h3' {
  // extend `DefineLocaleMessage` with `ResourceSchema`
  export interface DefineLocaleMessage extends ResourceSchema {}
}

const router = createRouter()
router.get(
  '/',
  eventHandler(async event => {
    const t = await useTranslation(event)
    // you can completion when you type `t('`
    return t('hello', { name: 'h3' })
  })
)

The advantage of this way is that it is not necessary to specify the resource schema in the useTranslation type parameter.

🛠️ Utilities & Helpers

@intlify/h3 has a concept of composable utilities & helpers.

See the API References

🙌 Contributing guidelines

If you are interested in contributing to @intlify/h3, I highly recommend checking out the contributing guidelines here. You'll find all the relevant information such as how to make a PR, how to setup development) etc., there.

©️ License

MIT