fix: sync cookie when setting locale

specs/browser_language_detection/no_prefix.spec.ts

@@ -38,6 +38,10 @@ test('detection with cookie', async () => {
   })
   const { page } = await renderPage('/', { locale: 'en' })
   const ctx = await page.context()
+  expect(await ctx.cookies()).toMatchObject([
+    { name: 'my_custom_cookie_name', value: 'en', secure: true, sameSite: 'None' }
+  ])
+
   // click `fr` lang switch link
   await page.locator('#set-locale-link-fr').click()
   expect(await ctx.cookies()).toMatchObject([

specs/browser_language_detection/prefix_and_default.spec.ts

@@ -110,6 +110,7 @@ test('alwaysRedirect: no prefix', async () => {
 
   // detect locale from navigator language
   expect(await getText(page, '#lang-switcher-current-locale code')).toEqual('en')
+  expect(await ctx.cookies()).toMatchObject([{ name: 'i18n_redirected', value: 'en' }])
 
   // click `fr` lang switch with nutlink
   await page.locator('#set-locale-link-fr').click()

specs/issues/2262.spec.ts

@@ -16,6 +16,7 @@ describe('#2262', async () => {
     const ctx = await page.context()
 
     expect(await getText(page, '#msg')).toEqual('Welcome')
+    expect(await ctx.cookies()).toMatchObject([{ name: 'i18n_redirected', value: 'en' }])
 
     // change to `fr`
     await page.locator('#fr').click()

src/runtime/plugins/i18n.ts

@@ -166,7 +166,7 @@ export default defineNuxtPlugin({
           )
           composer.setLocale = async (locale: string) => {
             const localeSetup = isInitialLocaleSetup(locale)
-            const [modified] = await loadAndSetLocale(locale, i18n, runtimeI18n, localeSetup)
+            const modified = await loadAndSetLocale(locale, i18n, runtimeI18n, localeSetup)
 
             if (modified && localeSetup) {
               notInitialSetup = false
@@ -450,7 +450,7 @@ export default defineNuxtPlugin({
         const localeSetup = isInitialLocaleSetup(locale)
         __DEBUG__ && console.log('localeSetup', localeSetup)
 
-        const [modified] = await loadAndSetLocale(locale, i18n, runtimeI18n, localeSetup)
+        const modified = await loadAndSetLocale(locale, i18n, runtimeI18n, localeSetup)
 
         if (modified && localeSetup) {
           notInitialSetup = false

src/runtime/utils.ts

@@ -107,39 +107,57 @@ export async function loadAndSetLocale(
   i18n: I18n,
   runtimeI18n: ModulePublicRuntimeConfig['i18n'],
   initial: boolean = false
-): Promise<[boolean, string]> {
+): Promise<boolean> {
   const { differentDomains, skipSettingLocaleOnNavigate, lazy } = runtimeI18n
   const opts = runtimeDetectBrowserLanguage(runtimeI18n)
   const nuxtApp = useNuxtApp()
 
-  let ret = false
   const oldLocale = getLocale(i18n)
+  const localeCodes = getLocaleCodes(i18n)
+
+  // sets the locale cookie if unset or not up to date
+  function syncCookie(locale: Locale = oldLocale) {
+    if (opts === false || !opts.useCookie) return
+    if (skipSettingLocaleOnNavigate) return
+
+    setCookieLocale(i18n, locale)
+  }
+
   __DEBUG__ && console.log('setLocale: new -> ', newLocale, ' old -> ', oldLocale, ' initial -> ', initial)
+
+  // `newLocale` is unset or empty
   if (!newLocale) {
-    return [ret, oldLocale]
+    syncCookie()
+    return false
   }
 
-  // abort if different domains option enabled
+  // no change if different domains option enabled
   if (!initial && differentDomains) {
-    return [ret, oldLocale]
+    syncCookie()
+    return false
   }
 
   if (oldLocale === newLocale) {
-    return [ret, oldLocale]
+    syncCookie()
+    return false
   }
 
-  // call onBeforeLanguageSwitch
+  // call `onBeforeLanguageSwitch` which may return an override for `newLocale`
   const localeOverride = await onBeforeLanguageSwitch(i18n, oldLocale, newLocale, initial, nuxtApp)
-  const localeCodes = getLocaleCodes(i18n)
-  if (localeOverride && localeCodes && localeCodes.includes(localeOverride)) {
-    if (localeOverride === oldLocale) {
-      return [ret, oldLocale]
+  if (localeOverride && localeCodes.includes(localeOverride)) {
+    // resolved `localeOverride` is already in use
+    if (oldLocale === localeOverride) {
+      syncCookie()
+      return false
     }
+
     newLocale = localeOverride
   }
 
-  const i18nFallbackLocales = getVueI18nPropertyValue<FallbackLocale>(i18n, 'fallbackLocale')
+  // load locale messages required by `newLocale`
   if (lazy) {
+    const i18nFallbackLocales = getVueI18nPropertyValue<FallbackLocale>(i18n, 'fallbackLocale')
+
     const setter = (locale: Locale, message: Record<string, any>) => mergeLocaleMessage(i18n, locale, message)
     if (i18nFallbackLocales) {
       const fallbackLocales = makeFallbackLocaleCodes(i18nFallbackLocales, [newLocale])
@@ -149,19 +167,16 @@ export async function loadAndSetLocale(
   }
 
   if (skipSettingLocaleOnNavigate) {
-    return [ret, oldLocale]
+    return false
   }
 
-  // set the locale
-  if (opts !== false && opts.useCookie) {
-    setCookieLocale(i18n, newLocale)
-  }
+  // sync cookie and set the locale
+  syncCookie(newLocale)
   setLocale(i18n, newLocale)
 
   await onLanguageSwitched(i18n, oldLocale, newLocale)
 
-  ret = true
-  return [ret, oldLocale]
+  return true
 }
 
 type LocaleLoader = () => Locale