feat: "onlyOnNoPrefix" - detect browser locale when no prefix

docs/content/en/options-reference.md

@@ -123,6 +123,7 @@ Supported properties:
 - `alwaysRedirect` (default: `false`) - Set to always redirect to the value stored in the cookie, not just on first visit.
 - `fallbackLocale` (default: `null`) - If none of the locales match the browser's locale, use this one as a fallback.
 - `onlyOnRoot` (default: `false`) - Set to `true` (recommended for improved SEO) to only attempt to detect the browser locale on the root path (`/`) of the site. Only effective when using strategy other than `'no_prefix'`.
+- `onlyOnNoPrefix` (default: `false`) - This is a more permissive variant of `onlyOnRoot` that will allow attempt to detect the browser locale on the root path (`/`) and also on paths that have no locale prefix (like `/foo`). Only effective when `onlyOnRoot` is not enabled and using strategy other than `'no_prefix'`.
 - `useCookie` (default: `true`) - If enabled, a cookie is set once the user has been redirected to browser's preferred locale, to prevent subsequent redirections. Set to `false` to redirect every time.
 - `cookieKey` (default: `'i18n_redirected'`) - Cookie name.
 - `cookieDomain` (default: `null`) - Set to override the default domain of the cookie. Defaults to the **host** of the site.

docs/content/es/options-reference.md

@@ -123,6 +123,7 @@ Supported properties:
 - `alwaysRedirect` (default: `false`) - Set to always redirect to the value stored in the cookie, not just on first visit.
 - `fallbackLocale` (default: `null`) - If none of the locales match the browser's locale, use this one as a fallback.
 - `onlyOnRoot` (default: `false`) - Set to `true` (recommended for improved SEO) to only attempt to detect the browser locale on the root path (`/`) of the site. Only effective when using strategy other than `'no_prefix'`.
+- `onlyOnNoPrefix` (default: `false`) - This is a more permissive variant of `onlyOnRoot` that will allow attempt to detect the browser locale on the root path (`/`) and also on paths that have no locale prefix (like `/foo`). Only effective when `onlyOnRoot` is not enabled and using strategy other than `'no_prefix'`.
 - `useCookie` (default: `true`) - If enabled, a cookie is set once the user has been redirected to browser's preferred locale, to prevent subsequent redirections. Set to `false` to redirect every time.
 - `cookieKey` (default: `'i18n_redirected'`) - Cookie name.
 - `cookieDomain` (default: `null`) - Set to override the default domain of the cookie. Defaults to the **host** of the site.

src/helpers/constants.js

@@ -38,6 +38,7 @@ exports.DEFAULT_OPTIONS = {
     cookieSecure: false,
     alwaysRedirect: false,
     fallbackLocale: '',
+    onlyOnNoPrefix: false,
     onlyOnRoot: false
   },
   differentDomains: false,

src/templates/plugin.main.js

@@ -28,6 +28,7 @@ import {
   createLocaleFromRouteGetter,
   getLocaleCookie,
   getLocaleDomain,
+  getLocalesRegex,
   resolveBaseUrl,
   matchBrowserLocale,
   parseAcceptLanguage,
@@ -38,7 +39,7 @@ import {
 
 Vue.use(VueI18n)
 
-const { alwaysRedirect, onlyOnRoot, fallbackLocale } = detectBrowserLanguage
+const { alwaysRedirect, onlyOnNoPrefix, onlyOnRoot, fallbackLocale } = detectBrowserLanguage
 const getLocaleFromRoute = createLocaleFromRouteGetter(localeCodes, { routesNameSeparator, defaultLocaleRouteNameSuffix })
 
 /** @type {import('@nuxt/types').Plugin} */
@@ -125,9 +126,9 @@ export default async (context) => {
     }
 
     if (getLocaleFromRoute(route) === locale) {
-      // If "onlyOnRoot" is set and strategy is "prefix_and_default", prefer unprefixed route for
+      // If "onlyOnRoot" or "onlyOnNoPrefix" is set and strategy is "prefix_and_default", prefer unprefixed route for
       // default locale.
-      if (!onlyOnRoot || locale !== defaultLocale || strategy !== STRATEGIES.PREFIX_AND_DEFAULT) {
+      if (!(onlyOnRoot || onlyOnNoPrefix) || locale !== defaultLocale || strategy !== STRATEGIES.PREFIX_AND_DEFAULT) {
         return ''
       }
     }
@@ -185,8 +186,16 @@ export default async (context) => {
       return false
     }
 
-    if (onlyOnRoot && strategy !== STRATEGIES.NO_PREFIX && route.path !== '/') {
-      return false
+    if (strategy !== STRATEGIES.NO_PREFIX) {
+      if (onlyOnRoot) {
+        if (route.path !== '/') {
+          return false
+        }
+      } else if (onlyOnNoPrefix) {
+        if (!alwaysRedirect && route.path.match(getLocalesRegex(localeCodes))) {
+          return false
+        }
+      }
     }
 
     let matchedLocale

src/templates/utils-common.js

@@ -103,6 +103,13 @@ export const getLocaleDomain = (locales, req, { localDomainKey, localeCodeKey })
   return null
 }
 
+/**
+ * Creates a RegExp for route paths
+ * @param  {string[]} localeCodes
+ * @return {RegExp}
+ */
+export const getLocalesRegex = localeCodes => new RegExp(`^/(${localeCodes.join('|')})(?:/|$)`, 'i')
+
 /**
  * Creates getter for getLocaleFromRoute
  * @param  {string[]} localeCodes
@@ -113,8 +120,7 @@ export const createLocaleFromRouteGetter = (localeCodes, { routesNameSeparator,
   const localesPattern = `(${localeCodes.join('|')})`
   const defaultSuffixPattern = `(?:${routesNameSeparator}${defaultLocaleRouteNameSuffix})?`
   const regexpName = new RegExp(`${routesNameSeparator}${localesPattern}${defaultSuffixPattern}$`, 'i')
-  const regexpPath = new RegExp(`^/${localesPattern}/`, 'i')
-
+  const regexpPath = getLocalesRegex(localeCodes)
   /**
    * Extract locale code from given route:
    * - If route has a name, try to extract locale from it

test/module.test.js

@@ -1034,6 +1034,17 @@ describe('no_prefix strategy', () => {
     const dom = getDom(html)
     expect(dom.querySelector('#current-locale')?.textContent).toBe('locale: en')
   })
+
+  test('does detect browser locale', async () => {
+    const requestOptions = {
+      headers: {
+        'Accept-Language': 'fr'
+      }
+    }
+    const html = await get('/', requestOptions)
+    const dom = getDom(html)
+    expect(dom.querySelector('#current-locale')?.textContent).toBe('locale: fr')
+  })
 })
 
 describe('no_prefix strategy + differentDomains', () => {
@@ -1511,6 +1522,107 @@ describe('no_prefix + detectBrowserLanguage + alwaysRedirect', () => {
   })
 })
 
+describe('prefix + detectBrowserLanguage', () => {
+  /** @type {Nuxt} */
+  let nuxt
+
+  beforeAll(async () => {
+    const override = {
+      i18n: {
+        defaultLocale: 'fr',
+        strategy: 'prefix',
+        detectBrowserLanguage: {
+          useCookie: true
+        }
+      }
+    }
+
+    nuxt = (await setup(loadConfig(__dirname, 'basic', override, { merge: true }))).nuxt
+  })
+
+  afterAll(async () => {
+    await nuxt.close()
+  })
+
+  test('redirects root even if the route already has a locale', async () => {
+    const requestOptions = {
+      followRedirect: false,
+      resolveWithFullResponse: true,
+      simple: false, // Don't reject on non-2xx response
+      headers: {
+        'Accept-Language': 'fr'
+      }
+    }
+    const response = await get('/en', requestOptions)
+    expect(response.statusCode).toBe(302)
+    expect(response.headers.location).toBe('/fr')
+  })
+
+  test('redirects subroute even if the route already has a locale', async () => {
+    const requestOptions = {
+      followRedirect: false,
+      resolveWithFullResponse: true,
+      simple: false, // Don't reject on non-2xx response
+      headers: {
+        'Accept-Language': 'fr'
+      }
+    }
+    const response = await get('/en/simple', requestOptions)
+    expect(response.statusCode).toBe(302)
+    expect(response.headers.location).toBe('/fr/simple')
+  })
+})
+
+describe('prefix + detectBrowserLanguage + onlyOnNoPrefix', () => {
+  /** @type {Nuxt} */
+  let nuxt
+
+  beforeAll(async () => {
+    const override = {
+      i18n: {
+        defaultLocale: 'fr',
+        strategy: 'prefix',
+        detectBrowserLanguage: {
+          useCookie: true,
+          onlyOnNoPrefix: true
+        }
+      }
+    }
+
+    nuxt = (await setup(loadConfig(__dirname, 'basic', override, { merge: true }))).nuxt
+  })
+
+  afterAll(async () => {
+    await nuxt.close()
+  })
+
+  test('does not redirect root if the route already has a locale', async () => {
+    const requestOptions = {
+      followRedirect: false,
+      resolveWithFullResponse: true,
+      simple: false, // Don't reject on non-2xx response
+      headers: {
+        'Accept-Language': 'fr'
+      }
+    }
+    const response = await get('/en', requestOptions)
+    expect(response.statusCode).toBe(200)
+  })
+
+  test('does not redirect subroute if the route already has a locale', async () => {
+    const requestOptions = {
+      followRedirect: false,
+      resolveWithFullResponse: true,
+      simple: false, // Don't reject on non-2xx response
+      headers: {
+        'Accept-Language': 'fr'
+      }
+    }
+    const response = await get('/en/simple', requestOptions)
+    expect(response.statusCode).toBe(200)
+  })
+})
+
 describe('prefix + detectBrowserLanguage + alwaysRedirect', () => {
   /** @type {Nuxt} */
   let nuxt
@@ -1539,6 +1651,20 @@ describe('prefix + detectBrowserLanguage + alwaysRedirect', () => {
     const dom = getDom(html)
     expect(dom.querySelector('#current-locale')?.textContent).toBe('locale: fr')
   })
+
+  test('redirects although the route already has a locale', async () => {
+    const requestOptions = {
+      followRedirect: false,
+      resolveWithFullResponse: true,
+      simple: false, // Don't reject on non-2xx response
+      headers: {
+        'Accept-Language': 'fr'
+      }
+    }
+    const response = await get('/en', requestOptions)
+    expect(response.statusCode).toBe(302)
+    expect(response.headers.location).toBe('/fr')
+  })
 })
 
 describe('generate with detectBrowserLanguage.fallbackLocale', () => {

types/nuxt-i18n.d.ts

@@ -34,6 +34,7 @@ declare namespace NuxtVueI18n {
       cookieKey?: string
       alwaysRedirect?: boolean
       fallbackLocale?: Locale | null
+      onlyOnNoPrefix?: boolean
       onlyOnRoot?: boolean
     }