title: facebook PHP or Javascript get the user logged in info
body: <p>I have a simple question : Can I get the username or some info of a user that is visiting my page if he is at the same time logged in at his facebook account?   </p>
  
  <p>I read about facebook graphe API but I'm not sure if it is requiring the user to login first into an app before we can get his info so basically I'm wondring if there is a PHP or javascript script that uses somehow facebook tools to detect if a visitor is logged in to facebook and catch his username if he is without asking him anything.</p>
  
  <p>Thanks.</p>