This hook is executed before Contao replaces the so called “script tags”, i.e.
[[TL_JQUERY]][[TL_MOOTOOLS]][[TL_BODY]][[TL_CSS]][[TL_HEAD]]These tags will be replaced according to the global arrays containing all the necessary JavaScript & CSS files etc. for the current page.
The hook allows you to replace these script tags yourself, or execute other custom code before the replacement.
Since Contao 4.13 a nonce value is added to the tag names resulting in tag names like [[TL_CSS_686b97e15f9e04213c87e53db3d7a8bd]]. The nonce value value can be retrieved from ContaoFramework::getNonce().
string $buffer
The buffer containing the current page output, with the dynamic script tags still in place.
A string containing the (modified) bufffer content.
// src/EventListener/ReplaceDynamicScriptTagsListener.php
namespace App\EventListener;
use Contao\CoreBundle\Framework\ContaoFramework;
use Contao\CoreBundle\ServiceAnnotation\Hook;
/**
* @Hook("replaceDynamicScriptTags")
*/
class ReplaceDynamicScriptTagsListener
{
public function __invoke(string $buffer): string
{
$nonce = '';
if (method_exists(ContaoFramework::class, 'getNonce')) {
$nonce = '_'.ContaoFramework::getNonce();
}
return str_replace("[[TL_CSS$nonce]]", "[[TL_CSS$nonce]]".'<link rel="stylesheet" href="assets/custom.css">', $buffer);
}
}