is it possible to differentiate with Google Analytics between logged in and logged out users? Can I even track the data of each unique user by sending the User ID somehow via JS? If yes, how?
You can redirect logged in user on a specific url
if a specific google analytics id than a logged out one:
<?php
if($user->isLoggedIn()) {
echo '
your google analytics code here for logged in users
'
;
} else {
echo '
your google analytics code here for public users
'
;
}
FOR EXAMPLE, in the google analytics documentation:
if (isset($userId)) {
$gacode = "ga('create', 'UA-XXXX-Y', { 'userId': '%s' });";
echo sprintf($gacode, $userId);
} else {
$gacode = "ga('create', 'UA-XXXX-Y');";
echo sprintf($gacode);
}
You can find more information here:
https://developers.google.com/analytics/devguides/collection/analyticsjs/user-id