Add browser locale redirect for website

website/docusaurus.config.ts

@@ -12,6 +12,7 @@ const config: Config = {
 
   organizationName: 'aliyun',
   projectName: 'iac-code',
+  clientModules: ['./src/clientModules/localeRedirect.js'],
 
   onBrokenLinks: 'throw',
   markdown: {

website/package.json

@@ -5,6 +5,7 @@
   "scripts": {
     "docusaurus": "docusaurus",
     "start": "docusaurus start",
+    "test": "node --test src/clientModules/*.test.cjs",
     "build": "docusaurus build",
     "serve": "docusaurus serve",
     "clear": "docusaurus clear",

website/src/clientModules/localeRedirect.js

@@ -0,0 +1,51 @@
+import siteConfig from '@generated/docusaurus.config';
+import redirectRules from './localeRedirectRules.cjs';
+
+const {getBrowserLocaleRedirect} = redirectRules;
+const storageKey = 'iac-code.localeRedirect.v1';
+
+function wasRedirectedInSession() {
+  try {
+    return window.sessionStorage.getItem(storageKey) === 'true';
+  } catch {
+    return false;
+  }
+}
+
+function markRedirectedInSession() {
+  try {
+    window.sessionStorage.setItem(storageKey, 'true');
+  } catch {
+    // Storage can be unavailable in strict browser privacy modes.
+  }
+}
+
+function getBrowserLanguages() {
+  if (Array.isArray(window.navigator.languages) && window.navigator.languages.length > 0) {
+    return window.navigator.languages;
+  }
+
+  return window.navigator.language ? [window.navigator.language] : [];
+}
+
+export function onRouteDidUpdate({location}) {
+  if (typeof window === 'undefined') {
+    return;
+  }
+
+  const redirectTo = getBrowserLocaleRedirect({
+    baseUrl: siteConfig.baseUrl,
+    defaultLocale: siteConfig.i18n.defaultLocale,
+    locales: siteConfig.i18n.locales,
+    pathname: location.pathname,
+    search: location.search,
+    hash: location.hash,
+    browserLanguages: getBrowserLanguages(),
+    alreadyRedirected: wasRedirectedInSession(),
+  });
+
+  if (redirectTo) {
+    markRedirectedInSession();
+    window.location.replace(redirectTo);
+  }
+}

website/src/clientModules/localeRedirect.test.cjs

@@ -0,0 +1,85 @@
+const assert = require('node:assert/strict');
+const test = require('node:test');
+
+const {
+  getBrowserLocaleRedirect,
+  selectPreferredLocale,
+} = require('./localeRedirectRules.cjs');
+
+const config = {
+  baseUrl: '/iac-code/',
+  defaultLocale: 'en',
+  locales: ['en', 'zh-Hans', 'ja', 'fr', 'de', 'es', 'pt'],
+};
+
+test('selectPreferredLocale maps browser language variants to configured locales', () => {
+  assert.equal(selectPreferredLocale(['zh-CN', 'en-US'], config), 'zh-Hans');
+  assert.equal(selectPreferredLocale(['ja-JP', 'en-US'], config), 'ja');
+  assert.equal(selectPreferredLocale(['pt-BR', 'en-US'], config), 'pt');
+  assert.equal(selectPreferredLocale(['it-IT', 'fr-FR'], config), 'fr');
+});
+
+test('selectPreferredLocale falls back to the default locale for unsupported languages', () => {
+  assert.equal(selectPreferredLocale(['it-IT'], config), 'en');
+});
+
+test('getBrowserLocaleRedirect redirects only the root page to a non-default browser locale', () => {
+  assert.equal(
+    getBrowserLocaleRedirect({
+      ...config,
+      pathname: '/iac-code/',
+      search: '?utm_source=test',
+      hash: '#top',
+      browserLanguages: ['zh-CN', 'en-US'],
+      alreadyRedirected: false,
+    }),
+    '/iac-code/zh-Hans/?utm_source=test#top',
+  );
+});
+
+test('getBrowserLocaleRedirect skips localized, non-root, default-locale, and already-redirected pages', () => {
+  assert.equal(
+    getBrowserLocaleRedirect({
+      ...config,
+      pathname: '/iac-code/zh-Hans/docs/intro',
+      search: '',
+      hash: '',
+      browserLanguages: ['zh-CN'],
+      alreadyRedirected: false,
+    }),
+    null,
+  );
+  assert.equal(
+    getBrowserLocaleRedirect({
+      ...config,
+      pathname: '/iac-code/docs/intro',
+      search: '',
+      hash: '',
+      browserLanguages: ['zh-CN'],
+      alreadyRedirected: false,
+    }),
+    null,
+  );
+  assert.equal(
+    getBrowserLocaleRedirect({
+      ...config,
+      pathname: '/iac-code/',
+      search: '',
+      hash: '',
+      browserLanguages: ['en-US'],
+      alreadyRedirected: false,
+    }),
+    null,
+  );
+  assert.equal(
+    getBrowserLocaleRedirect({
+      ...config,
+      pathname: '/iac-code/',
+      search: '',
+      hash: '',
+      browserLanguages: ['zh-CN'],
+      alreadyRedirected: true,
+    }),
+    null,
+  );
+});

website/src/clientModules/localeRedirectRules.cjs

@@ -0,0 +1,69 @@
+function normalizeBaseUrl(baseUrl) {
+  const withLeadingSlash = baseUrl.startsWith('/') ? baseUrl : `/${baseUrl}`;
+  return withLeadingSlash.endsWith('/') ? withLeadingSlash : `${withLeadingSlash}/`;
+}
+
+function normalizePathname(pathname) {
+  const withLeadingSlash = pathname.startsWith('/') ? pathname : `/${pathname}`;
+  return withLeadingSlash.endsWith('/index.html')
+    ? withLeadingSlash.slice(0, -'index.html'.length)
+    : withLeadingSlash;
+}
+
+function resolveConfiguredLocale(browserLanguage, locales) {
+  const normalized = browserLanguage.toLowerCase().replace('_', '-');
+  const localeByLowercase = new Map(locales.map((locale) => [locale.toLowerCase(), locale]));
+
+  if (normalized.startsWith('zh') && localeByLowercase.has('zh-hans')) {
+    return localeByLowercase.get('zh-hans');
+  }
+
+  const exactLocale = localeByLowercase.get(normalized);
+  if (exactLocale) {
+    return exactLocale;
+  }
+
+  const language = normalized.split('-')[0];
+  return localeByLowercase.get(language) ?? null;
+}
+
+function selectPreferredLocale(browserLanguages, config) {
+  for (const browserLanguage of browserLanguages) {
+    const locale = resolveConfiguredLocale(browserLanguage, config.locales);
+    if (locale) {
+      return locale;
+    }
+  }
+
+  return config.defaultLocale;
+}
+
+function isRootPath(pathname, baseUrl) {
+  const normalizedPathname = normalizePathname(pathname);
+  return normalizedPathname === normalizeBaseUrl(baseUrl);
+}
+
+function getBrowserLocaleRedirect({
+  pathname,
+  search = '',
+  hash = '',
+  browserLanguages,
+  alreadyRedirected,
+  ...config
+}) {
+  if (alreadyRedirected || !isRootPath(pathname, config.baseUrl)) {
+    return null;
+  }
+
+  const preferredLocale = selectPreferredLocale(browserLanguages, config);
+  if (preferredLocale === config.defaultLocale) {
+    return null;
+  }
+
+  return `${normalizeBaseUrl(config.baseUrl)}${preferredLocale}/${search}${hash}`;
+}
+
+module.exports = {
+  getBrowserLocaleRedirect,
+  selectPreferredLocale,
+};