fix: detectBrowserLanguage option (#2276)

resolve #2262
ref: #1888

specs/browser_language_detection/always_redirect/prefix_and_default_no_prefix.spec.ts

@@ -23,13 +23,15 @@ await setup({
 test('alwaysRedirect: no prefix', async () => {
   const page = await createPage(undefined, { locale: 'en' }) // set browser locale
   await page.goto(url('/about'))
+  const ctx = await page.context()
 
   // detect locale from navigator language
   expect(await getText(page, '#lang-switcher-current-locale code')).toEqual('en')
 
   // click `fr` lang switch with nutlink
   await page.locator('#set-locale-link-fr').click()
   expect(await getText(page, '#lang-switcher-current-locale code')).toEqual('fr')
+  expect(await ctx.cookies()).toMatchObject([{ name: 'i18n_redirected', value: 'fr' }])
 
   // go to `blog/article` page
   await page.goto(url('/blog/article'))

specs/fixtures/issues/1721/app.vue

@@ -6,7 +6,7 @@
       <li
         v-for="({ code, name }, i) in locales"
         :key="code"
-        :class="{ 'selected': code === locale }"
+        :class="{ selected: code === locale }"
         @click.prevent="setLocale(code)"
       >
         {{ name }}
@@ -16,7 +16,7 @@
 </template>
 
 <script setup>
-const { locale, locales, setLocale } = useI18n();
+const { locale, locales, setLocale } = useI18n()
 </script>
 
 <style>

specs/fixtures/issues/1888/app.vue

@@ -0,0 +1,55 @@
+<template>
+  <div>
+    <h3>Switch language:</h3>
+
+    <button
+      v-for="locale in availableLocales"
+      :id="locale.code"
+      :key="locale.code"
+      @click="$i18n.setLocale(locale.code)"
+    >
+      {{ locale.name }}
+    </button>
+
+    <hr />
+
+    <h3>Current language:</h3>
+    <p>
+      <img id="flag" :src="`/flags/${currentLocale.flag}.svg`" :alt="currentLocale.flag" :key="currentLocale.flag" />
+
+      <img
+        v-if="isMounted"
+        id="flag-mounted"
+        :src="`/flags/${currentLocale.flag}.svg`"
+        :alt="currentLocale.flag"
+        :key="currentLocale.flag"
+      />
+
+      <span>{{ currentLocale.name }}</span>
+    </p>
+
+    <hr />
+
+    <h3>Translation test</h3>
+    <p id="html-msg" v-html="$t('test')" :key="currentLocale" />
+    <p id="html-msg-mounted" v-html="$t('test')" v-if="isMounted" />
+    <p id="test-msg">{{ $t('test') }}</p>
+  </div>
+</template>
+
+<script lang="ts" setup>
+const i18n = useI18n()
+const availableLocales = computed(() => i18n.locales.value)
+const currentLocale = computed(() => availableLocales.value.find(({ code }) => code === i18n.locale.value))
+const isMounted = ref(false)
+onMounted(() => {
+  isMounted.value = true
+})
+</script>
+
+<style lang="css" scoped>
+button,
+img {
+  margin-right: 16px;
+}
+</style>

specs/fixtures/issues/1888/locales/en.json

@@ -0,0 +1,3 @@
+{
+  "test": "<strong>Translation</strong> example"
+}

specs/fixtures/issues/1888/locales/fr.json

@@ -0,0 +1,3 @@
+{
+  "test": "Exemple de <strong>traduction</strong>"
+}

specs/fixtures/issues/1888/locales/pl.json

@@ -0,0 +1,3 @@
+{
+  "test": "Przykład <strong>tłumaczenia</strong>"
+}

specs/fixtures/issues/1888/nuxt.config.ts

@@ -0,0 +1,36 @@
+// https://v3.nuxtjs.org/api/configuration/nuxt.config
+export default defineNuxtConfig({
+  modules: ['@nuxtjs/i18n'],
+  i18n: {
+    locales: [
+      {
+        code: 'en',
+        flag: 'us',
+        iso: 'en-US',
+        file: 'en.json',
+        name: 'English'
+      },
+      { code: 'pl', flag: 'pl', iso: 'pl-PL', file: 'pl.json', name: 'Polski' },
+      {
+        code: 'fr',
+        flag: 'fr',
+        iso: 'fr-FR',
+        file: 'fr.json',
+        name: 'Français'
+      }
+    ],
+    defaultLocale: 'en',
+    strategy: 'prefix_except_default',
+    langDir: 'locales',
+    compilation: {
+      strictMessage: false
+    },
+    detectBrowserLanguage: {
+      useCookie: true,
+      // cookieKey: 'locale',
+      // fallbackLocale: 'en',
+      alwaysRedirect: true,
+      redirectOn: 'root'
+    }
+  }
+})

specs/fixtures/issues/1888/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "nuxt3-test-issues-1888",
+  "private": true,
+  "scripts": {
+    "build": "nuxt build",
+    "dev": "nuxt dev",
+    "generate": "nuxt generate",
+    "preview": "nuxt preview"
+  },
+  "devDependencies": {
+    "@nuxtjs/i18n": "latest",
+    "nuxt": "latest"
+  }
+}

specs/fixtures/issues/2262/app.vue

@@ -0,0 +1,7 @@
+<template>
+  <div>
+    <NuxtLayout>
+      <NuxtPage></NuxtPage>
+    </NuxtLayout>
+  </div>
+</template>

specs/fixtures/issues/2262/i18n.config.ts

@@ -0,0 +1,12 @@
+export default defineI18nConfig(() => ({
+  legacy: false,
+  locale: 'en',
+  messages: {
+    en: {
+      welcome: 'Welcome'
+    },
+    fr: {
+      welcome: 'Bienvenue'
+    }
+  }
+}))

specs/fixtures/issues/2262/layouts/default.vue

@@ -0,0 +1,5 @@
+<template>
+  <div>
+    <slot />
+  </div>
+</template>

specs/fixtures/issues/2262/nuxt.config.ts

@@ -0,0 +1,25 @@
+// https://nuxt.com/docs/api/configuration/nuxt-config
+export default defineNuxtConfig({
+  devtools: { enabled: true },
+  modules: ['@nuxtjs/i18n'],
+  i18n: {
+    locales: [
+      {
+        code: 'en',
+        name: 'English'
+      },
+      {
+        code: 'fr',
+        name: 'Français'
+      }
+    ],
+    strategy: 'prefix_except_default',
+    defaultLocale: 'en',
+    detectBrowserLanguage: {
+      useCookie: true,
+      cookieKey: 'i18n_redirected',
+      redirectOn: 'root', // recommended
+      alwaysRedirect: true
+    }
+  }
+})

specs/fixtures/issues/2262/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "nuxt3-test-issues-2262",
+  "private": true,
+  "scripts": {
+    "build": "nuxt build",
+    "dev": "nuxt dev",
+    "generate": "nuxt generate",
+    "preview": "nuxt preview"
+  },
+  "devDependencies": {
+    "@nuxtjs/i18n": "latest",
+    "nuxt": "latest"
+  }
+}

specs/fixtures/issues/2262/pages/index.vue

@@ -0,0 +1,21 @@
+<script setup>
+const { locale, locales } = useI18n()
+const switchLocalePath = useSwitchLocalePath()
+const availableLocales = computed(() => {
+  return locales.value.filter(i => i.code !== locale.value)
+})
+</script>
+
+<template>
+  <div>
+    <NuxtLink
+      :id="locale.code"
+      v-for="locale in availableLocales"
+      :key="locale.code"
+      :to="switchLocalePath(locale.code)"
+      >{{ locale.name }}</NuxtLink
+    >
+  </div>
+
+  <p id="msg">{{ $t('welcome') }}</p>
+</template>

specs/issues/1888.spec.ts

@@ -0,0 +1,41 @@
+import { test, expect, describe } from 'vitest'
+import { fileURLToPath } from 'node:url'
+import { URL } from 'node:url'
+import { setup, url, createPage } from '../utils'
+import { getText } from '../helper'
+
+describe('#1888', async () => {
+  await setup({
+    rootDir: fileURLToPath(new URL(`../fixtures/issues/1888`, import.meta.url))
+  })
+
+  test('should be worked', async () => {
+    const home = url('/')
+    const page = await createPage(undefined, { locale: 'pl' })
+    await page.goto(home)
+
+    expect(await getText(page, '#html-msg')).toEqual('Przykład tłumaczenia')
+    expect(await getText(page, '#html-msg-mounted')).toEqual('Przykład tłumaczenia')
+    expect(await getText(page, '#test-msg')).toEqual('Przykład <strong>tłumaczenia</strong>')
+    expect(await page.locator('#flag').getAttribute('alt')).toContain('pl')
+    expect(await page.locator('#flag-mounted').getAttribute('alt')).toContain('pl')
+
+    // change to `en` locale
+    await page.locator('#en').click()
+
+    expect(await getText(page, '#html-msg')).toEqual('Translation example')
+    expect(await getText(page, '#html-msg-mounted')).toEqual('Translation example')
+    expect(await getText(page, '#test-msg')).toEqual('<strong>Translation</strong> example')
+    expect(await page.locator('#flag').getAttribute('alt')).toContain('us')
+    expect(await page.locator('#flag-mounted').getAttribute('alt')).toContain('us')
+
+    // change to `fr` locale
+    await page.locator('#fr').click()
+
+    expect(await getText(page, '#html-msg')).toEqual('Exemple de traduction')
+    expect(await getText(page, '#html-msg-mounted')).toEqual('Exemple de traduction')
+    expect(await getText(page, '#test-msg')).toEqual('Exemple de <strong>traduction</strong>')
+    expect(await page.locator('#flag').getAttribute('alt')).toContain('fr')
+    expect(await page.locator('#flag-mounted').getAttribute('alt')).toContain('fr')
+  })
+})

specs/issues/2262.spec.ts

@@ -0,0 +1,35 @@
+import { test, expect, describe } from 'vitest'
+import { fileURLToPath } from 'node:url'
+import { URL } from 'node:url'
+import { setup, url, createPage } from '../utils'
+import { getText } from '../helper'
+
+describe('#2262', async () => {
+  await setup({
+    rootDir: fileURLToPath(new URL(`../fixtures/issues/2262`, import.meta.url))
+  })
+
+  test('redirect with browser cookie', async () => {
+    const home = url('/')
+    const page = await createPage()
+    await page.goto(home)
+    const ctx = await page.context()
+
+    expect(await getText(page, '#msg')).toEqual('Welcome')
+
+    // change to `fr`
+    await page.locator('#fr').click()
+    expect(await getText(page, '#msg')).toEqual('Bienvenue')
+    expect(await ctx.cookies()).toMatchObject([{ name: 'i18n_redirected', value: 'fr' }])
+
+    // direct access to root `/`
+    await page.goto(home)
+    expect(await getText(page, '#msg')).toEqual('Bienvenue')
+    expect(page.url().endsWith('/fr'))
+
+    // change to `en`
+    await page.locator('#en').click()
+    expect(await getText(page, '#msg')).toEqual('Welcome')
+    expect(await ctx.cookies()).toMatchObject([{ name: 'i18n_redirected', value: 'en' }])
+  })
+})

src/runtime/internal.ts

@@ -308,6 +308,7 @@ export function setLocaleCookie(
 export type DetectBrowserLanguageNotDetectReason =
   | 'unknown'
   | 'not_found_match'
+  | 'first_access_only'
   | 'not_redirect_on_root'
   | 'not_redirect_on_no_prefix'
   | 'detect_ignore_on_ssg'
@@ -320,7 +321,11 @@ export type DetectBrowserLanguageFromResult = {
 }
 export type DetectLocaleForSSGStatus = 'ssg_ignore' | 'ssg_setup' | 'normal'
 export type DetectLocaleCallType = 'setup' | 'routing'
-export type DetectLocaleContext = { ssg: DetectLocaleForSSGStatus; callType: DetectLocaleCallType }
+export type DetectLocaleContext = {
+  ssg: DetectLocaleForSSGStatus
+  callType: DetectLocaleCallType
+  firstAccess: boolean
+}
 
 export const DefaultDetectBrowserLanguageFromResult: DetectBrowserLanguageFromResult = {
   locale: '',
@@ -339,14 +344,19 @@ export function detectBrowserLanguage<Context extends NuxtApp = NuxtApp>(
   locale: Locale = ''
 ): DetectBrowserLanguageFromResult {
   const { strategy } = nuxtI18nOptions
-  const { ssg, callType } = detectLocaleContext
-  __DEBUG__ && console.log('detectBrowserLanguage: (ssg, callType) - ', ssg, callType)
+  const { ssg, callType, firstAccess } = detectLocaleContext
+  __DEBUG__ && console.log('detectBrowserLanguage: (ssg, callType, firstAccess) - ', ssg, callType, firstAccess)
 
   // browser detection is ignored if it's a nuxt generate.
   if (isSSG && strategy === 'no_prefix' && (process.server || ssg === 'ssg_ignore')) {
     return { locale: '', stat: true, reason: 'detect_ignore_on_ssg' }
   }
 
+  // Locale detection from the browser is first access only
+  if (!firstAccess) {
+    return { locale: '', stat: false, reason: 'first_access_only' }
+  }
+
   const { redirectOn, alwaysRedirect, useCookie, fallbackLocale } =
     nuxtI18nOptions.detectBrowserLanguage as DetectBrowserLanguageOptions
 
@@ -360,6 +370,7 @@ export function detectBrowserLanguage<Context extends NuxtApp = NuxtApp>(
       redirectOn,
       locale
     )
+
   if (strategy !== 'no_prefix') {
     if (redirectOn === 'root') {
       if (path !== '/') {