system_js_settings_alter

system_js_settings_alter(&$settings, AttachedAssetsInterface $assets)

function system_js_settings_alter(&$settings, AttachedAssetsInterface $assets) {
  // As this is being output in the final response always use the master
  // request.
  $request = \Drupal::requestStack()->getMasterRequest();
  $current_query = $request->query->all();

  // Let output path processors set a prefix.
  /** @var \Drupal\Core\PathProcessor\OutboundPathProcessorInterface $path_processor */
  $path_processor = \Drupal::service('path_processor_manager');
  $options = ['prefix' => ''];
  $path_processor->processOutbound('/', $options);
  $pathPrefix = $options['prefix'];

  $route_match = \Drupal::routeMatch();
  if ($route_match instanceof StackedRouteMatchInterface) {
    $route_match = $route_match->getMasterRouteMatch();
  }
  $current_path = $route_match->getRouteName() ? Url::fromRouteMatch($route_match)->getInternalPath() : '';
  $current_path_is_admin = \Drupal::service('router.admin_context')->isAdminRoute($route_match->getRouteObject());
  $path_settings = [
    'baseUrl' => $request->getBaseUrl() . '/',
    'pathPrefix' => $pathPrefix,
    'currentPath' => $current_path,
    'currentPathIsAdmin' => $current_path_is_admin,
    'isFront' => \Drupal::service('path.matcher')->isFrontPage(),
    'currentLanguage' => \Drupal::languageManager()->getCurrentLanguage(LanguageInterface::TYPE_URL)->getId(),
  ];
  if (!empty($current_query)) {
    ksort($current_query);
    $path_settings['currentQuery'] = (object) $current_query;
  }

  // Only set core/drupalSettings values that haven't been set already.
  foreach ($path_settings as $key => $value) {
    if (!isset($settings['path'][$key])) {
      $settings['path'][$key] = $value;
    }
  }
  if (!isset($settings['pluralDelimiter'])) {
    $settings['pluralDelimiter'] = LOCALE_PLURAL_DELIMITER;
  }
  // Add the theme token to ajaxPageState, ensuring the database is available
  // before doing so. Also add the loaded libraries to ajaxPageState.
  /** @var \Drupal\Core\Asset\LibraryDependencyResolver $library_dependency_resolver */
  $library_dependency_resolver = \Drupal::service('library.dependency_resolver');
  if (isset($settings['ajaxPageState']) || in_array('core/drupal.ajax', $library_dependency_resolver->getLibrariesWithDependencies($assets->getAlreadyLoadedLibraries()))) {
    if (!defined('MAINTENANCE_MODE')) {
      // The theme token is only validated when the theme requested is not the
      // default, so don't generate it unless necessary.
      // @see \Drupal\Core\Theme\AjaxBasePageNegotiator::determineActiveTheme()
      $active_theme_key = \Drupal::theme()->getActiveTheme()->getName();
      if ($active_theme_key !== \Drupal::service('theme_handler')->getDefault()) {
        $settings['ajaxPageState']['theme_token'] = \Drupal::csrfToken()
          ->get($active_theme_key);
      }
    }
    // Provide the page with information about the individual asset libraries
    // used, information not otherwise available when aggregation is enabled.
    $minimal_libraries = $library_dependency_resolver->getMinimalRepresentativeSubset(array_merge(
    $assets->getLibraries(), 
    $assets->getAlreadyLoadedLibraries()
    ));
    sort($minimal_libraries);
    $settings['ajaxPageState']['libraries'] = implode(',', $minimal_libraries);
  }
}