SEO - @nuxtjs/i18n

Nuxt i18n module provides the useLocaleHead() composable function. Calling this composable function returns a function which you can use to generate SEO metadata to optimize locale-related aspects of the app for the search engines.

Here are the specific optimizations and features that it enables:

lang attribute for the <html> tag
hreflang alternate link generation
OpenGraph locale tag generation
canonical link generation

Requirements

To leverage the SEO benefits, you must configure the locales option as an array of objects, where each object has an language option set to the locale language tags:

nuxt.config.ts

export default defineNuxtConfig({
  i18n: {
    locales: [
      {
        code: 'en',
        language: 'en-US'
      },
      {
        code: 'es',
        language: 'es-ES'
      },
      {
        code: 'fr',
        language: 'fr-FR'
      }
    ]
  }
})

You must also set the baseUrl option to your production domain in order to make alternate URLs fully-qualified:

nuxt.config.ts

export default defineNuxtConfig({
  i18n: {
    baseUrl: 'https://my-nuxt-app.com'
  }
})

(Note that baseUrl can also be set to a function. Check baseUrl documentation.)

Setup

The useLocaleHead() is a composable function, Calling that composable function returns a function that returns metadata that is handled by Head management that is integrated within Nuxt. That metadata can be specified the setup function in various places within Nuxt:

app.vue
Vue components of pages directory
Vue components of layouts directory

To enable SEO metadata, declare a setup function in one of the places specified above and make it return the result of a useLocaleHead() function call.

To avoid duplicating the code, it's recommended to set globally with Meta Components in layout components and override some values per-page Vue component like definePageMeta(), if necessary.

<template>
  <NuxtLayout>
    <NuxtPage />
  </NuxtLayout>
</template>

Check out the options you can pass to the useLocaleHead() in the API documentation

That's it!

If you also want to add your own metadata, you have to call useHead(). When you call useHead() with the additional metadata, useHead() will merge it global metadata that has already defined.

pages/about/index.vue

<script setup>
// define page meta for layouts/default.vue
definePageMeta({
  title: 'pages.title.about'
})

useHead({
  meta: [{ property: 'og:title', content: 'this is og title for about page' }]
})
</script>

<template>
  <h2>{{ $t('pages.about.description') }}</h2>
</template>

Feature details

lang attribute for the <html> tag
Sets the correct lang attribute, equivalent to the current locale's language value, in the <html> tag.

hreflang alternate link
Generates <link rel="alternate" hreflang="x"> tags for every configured locale. The locales' language value are used as hreflang values.
A "catchall" locale hreflang link is provided for each locale group (e.g. en-*). By default, it is the first locale provided, but another locale can be selected by setting isCatchallLocale to true on that specific locale object in your Nuxt i18n module configuration. More on hreflang
An example without selected "catchall" locale:

nuxt.config.ts

export default defineNuxtConfig({
  i18n: {
    locales: [
      {
        code: 'en',
        language: 'en-US' // Will be used as "catchall" locale by default
      },
      {
        code: 'gb',
        language: 'en-GB'
      }
    ]
  }
})

Here is how you'd use isCatchallLocale to selected another locale:

nuxt.config.ts

export default defineNuxtConfig({
  i18n: {
    locales: [
      {
        code: 'en',
        language: 'en-US'
      },
      {
        code: 'gb',
        language: 'en-GB',
        isCatchallLocale: true // This one will be used as catchall locale
      }
    ]
  }
})

In case you already have an en locale language set, it'll be used as the "catchall" without doing anything

nuxt.config.ts

export default defineNuxtConfig({
  i18n: {
    locales: [
      {
        code: 'gb',
        language: 'en-GB'
      },
      {
        code: 'en',
        language: 'en' // will be used as "catchall" locale
      }
    ]
  }
})

OpenGraph Locale tag generation
Generates og:locale and og:locale:alternate meta tags as defined in the Open Graph protocol.
Canonical link
Generates rel="canonical" link on all pages to specify the "main" version of the page that should be indexed by search engines. This is beneficial in various situations:
- When using the prefix_and_default strategy there are technically two sets of pages generated for the default locale -- one prefixed and one unprefixed. The canonical link will be set to the unprefixed version of the page to avoid duplicate indexation.
- When the page contains query parameters, the canonical link will not include the query params by default. This is typically the right thing to do as various query params can be inserted by trackers and should not be part of the canonical link. This can be overridden by using the canonicalQueries option. For example:
```
<script setup>
const i18nHead = useLocaleHead({ seo: { canonicalQueries: ['foo'] } })
useHead(() => ({
  htmlAttrs: {
    lang: i18nHead.value.htmlAttrs!.lang
  },
  link: [...(i18nHead.value.link || [])],
  meta: [...(i18nHead.value.meta || [])]
}))
</script>
```
More on canonical

Browser language detection

Detect user browser's language.

Lazy-load translations

How to lazy-load translations.