How can I run javascript after user login in joomla 3?

Question

I try to use this function in a plugin, but is not working, maybe because javascript doesn't have time to execute after login an I end up redirected to homepage

 public function onUserAfterLogin($text) {
    $app = JFactory::getApplication();
    
    $document = JFactory::getDocument();
    $document->addScriptDeclaration('document.addEventListener("message", function(event) {
          alert("test");
        });
    ');
} 

I have tried with even with echo

echo '<script type="text/javascript">
   alert("test");
</script>';

Answer 1

One quick method is to redirect the user on login (this can be done at the menu item level) to a static HTML page/or a dynamic PHP page (depending on your needs) that contain the JavaScript code, and that page can then redirect to the page of your choice after firing the JS code.

Answer 2

thank you for the sugestion, but I've used the function in joomla onAfterRender() , and inside the function you can do this:

//This event is triggered after the framework has rendered the application.
//When this event is triggered the output of the application is available in the response buffer.
public function onAfterRender() {
$app = JFactory::getApplication();
$user_id = JFactory::getUser()->id; // NOT 0
$is_guest = JFactory::getUser()->guest; 
if ($user_id !== 0 && $is_guest !== 'guest') {
  $myJScript = 'alert("Test");';
  // retrieve all the response as an html string
  $html = $app->getBody();
  // Search and replace tag </body> with the new script+</body>
  $html = str_replace('</body>','<script type="text/javascript">' . $myJScript . '</script></body>', $html);
  // override the original response
  $app->setBody($html);
 }
}