AddCssCommand.php

<?php

namespace Drupal\Core\Ajax;


/**
 * An AJAX command for adding css to the page via ajax.
 *
 * This command is implemented by Drupal.AjaxCommands.prototype.add_css()
 * defined in misc/ajax.js.
 *
 * @see misc/ajax.js
 *
 * @ingroup ajax
 */
class AddCssCommand implements CommandInterface {
    
    /**
     * A string that contains the styles to be added to the page.
     *
     * It should include the wrapping style tag.
     *
     * @var string
     */
    protected $styles;
    
    /**
     * Constructs an AddCssCommand.
     *
     * @param string $styles
     *   A string that contains the styles to be added to the page, including the
     *   wrapping <style> tag.
     */
    public function __construct($styles) {
        $this->styles = $styles;
    }
    
    /**
     * Implements Drupal\Core\Ajax\CommandInterface:render().
     */
    public function render() {
        return [
            'command' => 'add_css',
            'data' => $this->styles,
        ];
    }

}