BeforeCommand.php

<?php

namespace Drupal\Core\Ajax;


/**
 * An AJAX command for calling the jQuery before() method.
 *
 * The 'insert/before' command instructs the client to use jQuery's before()
 * method to insert the given render array or HTML content before each of
 * elements matched by the given selector.
 *
 * This command is implemented by Drupal.AjaxCommands.prototype.insert()
 * defined in misc/ajax.js.
 *
 * @see http://docs.jquery.com/Manipulation/before#content
 *
 * @ingroup ajax
 */
class BeforeCommand extends InsertCommand {
    
    /**
     * Implements Drupal\Core\Ajax\CommandInterface:render().
     */
    public function render() {
        return [
            'command' => 'insert',
            'method' => 'before',
            'selector' => $this->selector,
            'data' => $this->getRenderedContent(),
            'settings' => $this->settings,
        ];
    }

}