Add language URL rewriting script for versioned docs and special chan…

docs/docs/javascripts/modify-lang-a-href.js

@@ -0,0 +1,50 @@
+window.addEventListener('DOMContentLoaded', function() {
+  // Handles language URL rewrites for:
+  // 1) Versioned docs (e.g. /v0.1.1/...).
+  // 2) Special channels such as /latest/.
+  // 3) Pages that already contain a language segment.
+  // 4) Root-level pages without explicit versioning.
+  const CONFIG = Object.freeze({
+    languages: ['en', 'zh'],
+    langSelector: 'a[hreflang="en"], a[hreflang="zh"]',
+    versionPattern: /^v?\d+(\.\d+)*$/i,
+    specialVersions: ['latest'],
+  });
+
+  const langAnchors = document.querySelectorAll(CONFIG.langSelector);
+  const currentPath = window.location.pathname || '/';
+  const hasTrailingSlash = currentPath.endsWith('/') && currentPath !== '/';
+  const rawSegments = currentPath.split('/').filter(Boolean);
+  let languageRemoved = false;
+  const sanitizedSegments = rawSegments.filter(function(segment) {
+    if (!languageRemoved && CONFIG.languages.includes(segment)) {
+      languageRemoved = true;
+      return false;
+    }
+    return true;
+  });
+  const insertIndex =
+    sanitizedSegments.length &&
+    (CONFIG.versionPattern.test(sanitizedSegments[0]) ||
+      CONFIG.specialVersions.includes(sanitizedSegments[0].toLowerCase()))
+      ? 1
+      : 0;
+  const searchAndHash = (window.location.search || '') + (window.location.hash || '');
+
+  function buildLocalizedPath(lang) {
+    const segments = sanitizedSegments.slice();
+    segments.splice(insertIndex, 0, lang);
+    const basePath = '/' + segments.join('/');
+    const normalizedPath = segments.length ? basePath : '/';
+    const finalPath = hasTrailingSlash && normalizedPath !== '/' ? normalizedPath + '/' : normalizedPath;
+    return finalPath + searchAndHash;
+  }
+
+  langAnchors.forEach(function(anchor) {
+    const lang = anchor.getAttribute('hreflang');
+    if (!lang || !CONFIG.languages.includes(lang)) {
+      return;
+    }
+    anchor.setAttribute('href', buildLocalizedPath(lang));
+  });
+});

docs/scripts/mkdocs_template.yml

@@ -250,3 +250,4 @@ extra_javascript:
   - javascripts/mathjax.js
   - javascripts/polyfill.min.js
   - javascripts/tex-mml-chtml.js
+  - javascripts/modify-lang-a-href.js