Add noindex for untranslated sites

Author: gaearon

src/components/Seo.tsx

@@ -22,8 +22,18 @@ const deployedTranslations = [
   'zh-hans',
   'es',
   // We'll add more languages when they have enough content.
+  // Please DO NOT edit this list without a discussion in the reactjs/react.dev repo.
+  // It must be the same between all translations.
 ];
 
+let shouldPreventIndexing = false;
+if (
+  siteConfig.languageCode !== 'en' &&
+  !deployedTranslations.includes(siteConfig.languageCode)
+) {
+  shouldPreventIndexing = true;
+}
+
 function getDomain(languageCode: string): string {
   const subdomain = languageCode === 'en' ? '' : languageCode + '.';
   return subdomain + 'react.dev';
@@ -59,6 +69,7 @@ export const Seo = withRouter(
           href={canonicalUrl.replace(siteDomain, getDomain('en'))}
           hrefLang="x-default"
         />
+        {shouldPreventIndexing && <meta name="robots" content="noindex" />}
         {deployedTranslations.map((languageCode) => (
           <link
             key={'alt-' + languageCode}