--- /dev/null
+<?php
+
+namespace Drupal\advagg\Asset;
+
+use Drupal\Component\Serialization\Json;
+use Drupal\Core\Asset\AssetCollectionRendererInterface;
+use Drupal\Core\Asset\JsCollectionRenderer as CoreJsCollectionRenderer;
+use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\State\StateInterface;
+
+/**
+ * {@inheritdoc}
+ */
+class JsCollectionRenderer extends CoreJsCollectionRenderer implements AssetCollectionRendererInterface {
+
+ /**
+ * A config object for the advagg configuration.
+ *
+ * @var \Drupal\Core\Config\Config
+ */
+ protected $config;
+
+ /**
+ * {@inheritdoc}
+ *
+ * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
+ * A config factory for retrieving required config objects.
+ */
+ public function __construct(StateInterface $state, ConfigFactoryInterface $config_factory) {
+ $this->state = $state;
+ $this->config = $config_factory->get('advagg.settings');
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function render(array $js_assets) {
+ // Check assets array to ensure that it isn't malformed.
+ if (isset($js_assets['-1']) && empty($js_assets[-1])) {
+ unset($js_assets['-1']);
+ }
+
+ $elements = ['prefetch' => []];
+ $prefetch = $this->config->get('dns_prefetch');
+
+ // A dummy query-string is added to filenames, to gain control over
+ // browser-caching. The string changes on every update or full cache
+ // flush, forcing browsers to load a new copy of the files, as the
+ // URL changed. Files that should not be cached get REQUEST_TIME as
+ // query-string instead, to enforce reload on every page request.
+ $default_query_string = $this->state->get('system.css_js_query_string') ?: '0';
+
+ // Defaults for each element.
+ $element_defaults = [
+ '#type' => 'html_tag',
+ '#tag' => 'script',
+ '#value' => '',
+ ];
+ $prefetch_element_defaults = [
+ '#type' => 'html_tag',
+ '#tag' => 'link',
+ '#attributes' => [
+ 'rel' => 'dns-prefetch',
+ ],
+ ];
+
+ // Loop through all JS assets.
+ foreach ($js_assets as $js_asset) {
+ // Element properties that do not depend on JS asset type.
+ $element = $element_defaults;
+ $element['#browsers'] = $js_asset['browsers'];
+
+ // Element properties that depend on item type.
+ switch ($js_asset['type']) {
+ case 'setting':
+ $element['#attributes'] = [
+ // This type attribute prevents this from being parsed as an
+ // inline script.
+ 'type' => 'application/json',
+ 'data-drupal-selector' => 'drupal-settings-json',
+ ];
+ $element['#value'] = Json::encode($js_asset['data']);
+ break;
+
+ case 'file':
+ $query_string = $js_asset['version'] == -1 ? $default_query_string : 'v=' . $js_asset['version'];
+ $query_string_separator = (strpos($js_asset['data'], '?') !== FALSE) ? '&' : '?';
+ $element['#attributes']['src'] = file_url_transform_relative(file_create_url($js_asset['data']));
+ // Only add the cache-busting query string if this isn't an aggregate
+ // file.
+ if (!isset($js_asset['preprocessed'])) {
+ $element['#attributes']['src'] .= $query_string_separator . ($js_asset['cache'] ? $query_string : REQUEST_TIME);
+ }
+ $element['#inline'] = !empty($js_asset['inline']) ? TRUE : FALSE;
+ break;
+
+ case 'external':
+ $element['#attributes']['src'] = $js_asset['data'];
+ if ($prefetch) {
+ $pre_element = $prefetch_element_defaults;
+ $pre_element['#attributes']['href'] = '//' . parse_url($js_asset['data'], PHP_URL_HOST);
+ $elements['prefetch'][] = $pre_element;
+ }
+ break;
+
+ default:
+ throw new \Exception('Invalid JS asset type.');
+ }
+
+ // Attributes may only be set if this script is output independently.
+ if (!empty($element['#attributes']['src']) && !empty($js_asset['attributes'])) {
+ $element['#attributes'] += $js_asset['attributes'];
+ }
+
+ $elements[] = $element;
+ }
+ if (empty($elements['prefetch'])) {
+ unset($elements['prefetch']);
+ }
+ return $elements;
+ }
+
+}