AssetResolver::getJsAssets

public AssetResolver::getJsAssets(AttachedAssetsInterface $assets, $optimize)

public function getJsAssets(AttachedAssetsInterface $assets, $optimize) {
  $theme_info = $this->themeManager->getActiveTheme();
  // Add the theme name to the cache key since themes may implement
  // hook_library_info_alter(). Additionally add the current language to
  // support translation of JavaScript files via hook_js_alter().
  $libraries_to_load = $this->getLibrariesToLoad($assets);
  $cid = 'js:' . $theme_info->getName() . ':' . $this->languageManager->getCurrentLanguage()->getId() . ':' . Crypt::hashBase64(serialize($libraries_to_load)) . (int) (count($assets->getSettings()) > 0) . (int) $optimize;

  if ($cached = $this->cache->get($cid)) {
    list($js_assets_header, $js_assets_footer, $settings, $settings_in_header) = $cached->data;
  }
  else {
    $javascript = [];
    $default_options = [
      'type' => 'file',
      'group' => JS_DEFAULT,
      'weight' => 0,
      'cache' => TRUE,
      'preprocess' => TRUE,
      'attributes' => [],
      'version' => NULL,
      'browsers' => [],
    ];

    // Collect all libraries that contain JS assets and are in the header.
    $header_js_libraries = [];
    foreach ($libraries_to_load as $library) {
      list($extension, $name) = explode('/', $library, 2);
      $definition = $this->libraryDiscovery->getLibraryByName($extension, $name);
      if (isset($definition['js']) && !empty($definition['header'])) {
        $header_js_libraries[] = $library;
      }
    }
    // The current list of header JS libraries are only those libraries that
    // are in the header, but their dependencies must also be loaded for them
    // to function correctly, so update the list with those.
    $header_js_libraries = $this->libraryDependencyResolver->getLibrariesWithDependencies($header_js_libraries);

    foreach ($libraries_to_load as $library) {
      list($extension, $name) = explode('/', $library, 2);
      $definition = $this->libraryDiscovery->getLibraryByName($extension, $name);
      if (isset($definition['js'])) {
        foreach ($definition['js'] as $options) {
          $options += $default_options;

          // 'scope' is a calculated option, based on which libraries are
          // marked to be loaded from the header (see above).
          $options['scope'] = in_array($library, $header_js_libraries) ? 'header' : 'footer';

          // Preprocess can only be set if caching is enabled and no
          // attributes are set.
          $options['preprocess'] = $options['cache'] && empty($options['attributes']) ? $options['preprocess'] : FALSE;

          // Always add a tiny value to the weight, to conserve the insertion
          // order.
          $options['weight'] += count($javascript) / 1000;

          // Local and external files must keep their name as the associative
          // key so the same JavaScript file is not added twice.
          $javascript[$options['data']] = $options;
        }
      }
    }

    // Allow modules and themes to alter the JavaScript assets.
    $this->moduleHandler->alter('js', $javascript, $assets);
    $this->themeManager->alter('js', $javascript, $assets);

    // Sort JavaScript assets, so that they appear in the correct order.
    uasort($javascript, 'static::sort');

    // Prepare the return value: filter JavaScript assets per scope.
    $js_assets_header = [];
    $js_assets_footer = [];
    foreach ($javascript as $key => $item) {
      if ($item['scope'] == 'header') {
        $js_assets_header[$key] = $item;
      }
      elseif ($item['scope'] == 'footer') {
        $js_assets_footer[$key] = $item;
      }
    }

    if ($optimize) {
      $collection_optimizer = \Drupal::service('asset.js.collection_optimizer');
      $js_assets_header = $collection_optimizer->optimize($js_assets_header);
      $js_assets_footer = $collection_optimizer->optimize($js_assets_footer);
    }

    // If the core/drupalSettings library is being loaded or is already
    // loaded, get the JavaScript settings assets, and convert them into a
    // single "regular" JavaScript asset.
    $libraries_to_load = $this->getLibrariesToLoad($assets);
    $settings_required = in_array('core/drupalSettings', $libraries_to_load) || in_array('core/drupalSettings', $this->libraryDependencyResolver->getLibrariesWithDependencies($assets->getAlreadyLoadedLibraries()));
    $settings_have_changed = count($libraries_to_load) > 0 || count($assets->getSettings()) > 0;

    // Initialize settings to FALSE since they are not needed by default. This
    // distinguishes between an empty array which must still allow
    // hook_js_settings_alter() to be run.
    $settings = FALSE;
    if ($settings_required && $settings_have_changed) {
      $settings = $this->getJsSettingsAssets($assets);
      // Allow modules to add cached JavaScript settings.
      foreach ($this->moduleHandler->getImplementations('js_settings_build') as $module) {
        $function = $module . '_' . 'js_settings_build';
        $function($settings, $assets);
      }
    }
    $settings_in_header = in_array('core/drupalSettings', $header_js_libraries);
    $this->cache->set($cid, [$js_assets_header, $js_assets_footer, $settings, $settings_in_header], CacheBackendInterface::CACHE_PERMANENT, ['library_info']);
  }

  if ($settings !== FALSE) {
    // Attached settings override both library definitions and
    // hook_js_settings_build().
    $settings = NestedArray::mergeDeepArray([$settings, $assets->getSettings()], TRUE);
    // Allow modules and themes to alter the JavaScript settings.
    $this->moduleHandler->alter('js_settings', $settings, $assets);
    $this->themeManager->alter('js_settings', $settings, $assets);
    // Update the $assets object accordingly, so that it reflects the final
    // settings.
    $assets->setSettings($settings);
    $settings_as_inline_javascript = [
      'type' => 'setting',
      'group' => JS_SETTING,
      'weight' => 0,
      'browsers' => [],
      'data' => $settings,
    ];
    $settings_js_asset = ['drupalSettings' => $settings_as_inline_javascript];
    // Prepend to the list of JS assets, to render it first. Preferably in
    // the footer, but in the header if necessary.
    if ($settings_in_header) {
      $js_assets_header = $settings_js_asset + $js_assets_header;
    }
    else {
      $js_assets_footer = $settings_js_asset + $js_assets_footer;
    }
  }
  return [
    $js_assets_header,
    $js_assets_footer,
  ];
}