/** * Renders a placeholder, and just that placeholder. * * BigPipe renders placeholders independently of the rest of the content, so * it needs to be able to render placeholders by themselves. * * @param string $placeholder * The placeholder to render. * @param array $placeholder_render_array * The render array associated with that placeholder. * * @return array * The render array representing the rendered placeholder. * * @see \Drupal\Core\Render\RendererInterface::renderPlaceholder() */ protected function renderPlaceholder($placeholder, array $placeholder_render_array) { $elements = ['#markup' => $placeholder, '#attached' => ['placeholders' => [$placeholder => $placeholder_render_array]]]; return $this->renderer->renderPlaceholder($placeholder, $elements); }