[LifesGreatestGift]

cant you just use a php widget and do this

PHP Code:

if ($vbulletin->userinfo['userid'] > 0) {
    $username = $vbulletin->userinfo['username'];
    echo 'Welcome ' . $username . '!';
} else {
    echo 'Welcome Guest!';
} 


P.S. I doubt the code above works, its a proof of concept.

Try this if you want to stick to JS

var username =$vbulletin->bbuserinfo['username'];

not sure if single quotes are needed in JS.