JsCollectionRenderer.php

<?php

namespace Drupal\Core\Asset;

use Drupal\Component\Serialization\Json;
use Drupal\Core\State\StateInterface;

/**
 * Renders JavaScript assets.
 */
class JsCollectionRenderer implements AssetCollectionRendererInterface {
    
    /**
     * The state key/value store.
     *
     * @var \Drupal\Core\State\StateInterface
     */
    protected $state;
    
    /**
     * Constructs a JsCollectionRenderer.
     *
     * @param \Drupal\Core\State\StateInterface $state
     *   The state key/value store.
     */
    public function __construct(StateInterface $state) {
        $this->state = $state;
    }
    
    /**
     * {@inheritdoc}
     *
     * This class evaluates the aggregation enabled/disabled condition on a group
     * by group basis by testing whether an aggregate file has been made for the
     * group rather than by testing the site-wide aggregation setting. This allows
     * this class to work correctly even if modules have implemented custom
     * logic for grouping and aggregating files.
     */
    public function render(array $js_assets) {
        $elements = [];
        // 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 SCRIPT element.
        $element_defaults = [
            '#type' => 'html_tag',
            '#tag' => 'script',
            '#value' => '',
        ];
        // Loop through all JS assets.
        foreach ($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);
                    }
                    break;
                case 'external':
                    $element['#attributes']['src'] = $js_asset['data'];
                    break;
                default:
                    throw new \Exception('Invalid JS asset type.');
            }
            // Attributes may only be set if this script is output independently.
            if (!empty($element['#attributes']['src']) && !empty($js_asset['attributes'])) {
                $element['#attributes'] += $js_asset['attributes'];
            }
            $elements[] = $element;
        }
        return $elements;
    }

}