Add static site QA checks

scripts/check-no-js.mjs

@@ -0,0 +1,80 @@
+import { readdir, readFile, stat } from 'node:fs/promises';
+import path from 'node:path';
+
+const dist = path.resolve('dist');
+const failures = [];
+
+async function walk(dir) {
+  const entries = await readdir(dir, { withFileTypes: true });
+  const files = [];
+
+  for (const entry of entries) {
+    const fullPath = path.join(dir, entry.name);
+    if (entry.isDirectory()) {
+      files.push(...(await walk(fullPath)));
+    } else {
+      files.push(fullPath);
+    }
+  }
+
+  return files;
+}
+
+try {
+  await stat(dist);
+} catch {
+  throw new Error('dist/ does not exist. Run npm run build first.');
+}
+
+const files = await walk(dist);
+const jsFiles = files.filter((file) => file.endsWith('.js'));
+
+if (jsFiles.length > 0) {
+  failures.push(
+    `Unexpected JavaScript assets:\n${jsFiles.map((file) => `- ${file}`).join('\n')}`
+  );
+}
+
+// Script tags are only allowed if they declare one of these safe `type`
+// attributes (or are tagged with `data-theme-script`). All other scripts —
+// including untyped ones, which default to executable JavaScript — are
+// flagged.
+const SAFE_SCRIPT_TYPES = new Set([
+  'application/ld+json',
+  'importmap',
+  'speculationrules',
+]);
+
+function isSafeScriptTag(tag) {
+  if (tag.includes('data-theme-script')) return true;
+  const typeMatch = tag.match(/\btype=["']([^"']+)["']/i);
+  if (!typeMatch) return false;
+  return SAFE_SCRIPT_TYPES.has(typeMatch[1].trim().toLowerCase());
+}
+
+for (const file of files.filter((candidate) => candidate.endsWith('.html'))) {
+  const html = await readFile(file, 'utf8');
+  const scripts = (html.match(/<script\b[^>]*>/gi) ?? []).filter(
+    (tag) => !isSafeScriptTag(tag)
+  );
+  if (scripts.length) {
+    failures.push(`Unexpected script tag in ${file}:\n${scripts.join('\n')}`);
+  }
+
+  // Inline event handlers (onclick=, onload=, etc.) execute JavaScript even
+  // without a <script> tag, so flag any attribute matching `on*=`. We strip
+  // <script> blocks first to avoid false positives from JSON-LD payloads.
+  const stripped = html.replace(/<script\b[\s\S]*?<\/script>/gi, '');
+  const handlerMatches = stripped.match(/\son\w+=/gi);
+  if (handlerMatches?.length) {
+    const unique = [...new Set(handlerMatches.map((m) => m.trim()))];
+    failures.push(`Unexpected inline event handler in ${file}:\n${unique.join('\n')}`);
+  }
+}
+
+if (failures.length > 0) {
+  console.error(failures.join('\n\n'));
+  process.exit(1);
+}
+
+console.log('No unexpected JavaScript found in dist/.');