class DeferCss in Advanced CSS/JS Aggregation 8.3

Modify stylesheet links to defer them. May lead to Flash of unstyled content.

Hierarchy

• class \Drupal\advagg_mod\Asset\DeferCss

1 file declares its use of DeferCss

InitSubscriber.php in advagg_mod/src/EventSubscriber/InitSubscriber.php

1 string reference to 'DeferCss'

advagg_mod.services.yml in advagg_mod/advagg_mod.services.yml

advagg_mod/advagg_mod.services.yml

1 service uses DeferCss

advagg_mod.defer_css in advagg_mod/advagg_mod.services.yml

Drupal\advagg_mod\Asset\DeferCss

File

advagg_mod/src/Asset/DeferCss.php, line 11

Namespace

Drupal\advagg_mod\Asset

class DeferCss {

  /**
   * The defer method to use from advagg_mod configuration.
   *
   * @var int
   */
  protected $deferMethod;

  /**
   * The global counter to use for calculating paths.
   *
   * @var int
   */
  protected $counter;

  /**
   * Whether or not to alter external stylesheets.
   *
   * @var bool
   */
  protected $external;

  /**
   * DeferCss constructor.
   *
   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
   *   The config factory.
   */
  public function __construct(ConfigFactoryInterface $config_factory) {
    $this->deferMethod = $config_factory
      ->get('advagg_mod.settings')
      ->get('css_defer_js_code');
    $this->counter = $config_factory
      ->get('advagg.settings')
      ->get('global_counter');
    $this->external = $config_factory
      ->get('advagg_mod.settings')
      ->get('css_defer_external');
  }

  /**
   * Replace stylesheet links with preload & noscript links.
   *
   * @param string $content
   *   The response content.
   *
   * @return string
   *   Updated content.
   */
  public function defer($content) {
    if ($this->external) {
      $pattern = '/<link rel=["\']stylesheet["\'](.*)(href="[a-zA-Z0-9\\/_\\.\\-\\?\\:]*")(.*)\\/\\>/';
    }
    else {
      $pattern = '/<link rel=["\']stylesheet["\'](.*)(href="\\/[a-zA-Z0-9][a-zA-Z0-9\\/_\\.\\-\\?]*")(.*)\\/\\>/';
    }
    $content = preg_replace_callback($pattern, [
      $this,
      'callback',
    ], $content);

    // Put JS inline if configured.
    if ($this->deferMethod === 0) {
      $path = drupal_get_path('module', 'advagg_mod') . '/js/loadCSS.js';
      if (!strpos($content, $path)) {
        $path = Crypt::hashBase64($path . $this->counter);
      }
      $path = preg_quote($path, '/');
      $pattern = "/<script src=['\"]\\/(.*{$path}.*)\\?.*['\"]>/";
      $content = preg_replace_callback($pattern, [
        $this,
        'inlineScript',
      ], $content);
    }
    return $content;
  }

  /**
   * Callback to replace individual stylesheet links.
   *
   * @param array $matches
   *   Array from matches from preg_replace_callback.
   *
   * @return string
   *   Updated html string.
   */
  protected function callback(array $matches) {
    return "<link rel='preload' {$matches[1]} {$matches[2]} as='style' onload=\"this.rel='stylesheet'\" {$matches[3]}/><noscript>{$matches[0]}</noscript>";
  }

  /**
   * Callback to replace the script link with an inline script.
   *
   * @param array $matches
   *   Array from matches from preg_replace_callback.
   *
   * @return string
   *   Updated html string.
   */
  protected function inlineScript(array $matches) {
    $data = @file_get_contents($matches[1]);
    return "<script>{$data}";
  }

}

Members

Name	Modifiers	Type	Description	Overrides
DeferCss::$counter	protected	property	The global counter to use for calculating paths.
DeferCss::$deferMethod	protected	property	The defer method to use from advagg_mod configuration.
DeferCss::$external	protected	property	Whether or not to alter external stylesheets.
DeferCss::callback	protected	function	Callback to replace individual stylesheet links.
DeferCss::defer	public	function	Replace stylesheet links with preload & noscript links.
DeferCss::inlineScript	protected	function	Callback to replace the script link with an inline script.
DeferCss::__construct	public	function	DeferCss constructor.