locale_preprocess_node

locale_preprocess_node(&$variables)

function locale_preprocess_node(&$variables) {
  /* @var $node \Drupal\node\NodeInterface */
  $node = $variables['node'];
  if ($node->language()->getId() != LanguageInterface::LANGCODE_NOT_SPECIFIED) {
    $interface_language = \Drupal::languageManager()->getCurrentLanguage();

    $node_language = $node->language();
    if ($node_language->getId() != $interface_language->getId()) {
      // If the node language was different from the page language, we should
      // add markup to identify the language. Otherwise the page language is
      // inherited.
      $variables['attributes']['lang'] = $node_language->getId();
      if ($node_language->getDirection() != $interface_language->getDirection()) {
        // If text direction is different form the page's text direction, add
        // direction information as well.
        $variables['attributes']['dir'] = $node_language->getDirection();
      }
    }
  }
}