<fb:login-button v="2" size="large" autologoutlink="false" onlogin="window.location='/index.php'">Connect with Facebook</fb:login-button>

<fb:name uid="loggedinuser" linked="true" firstnameonly="false" possessive="false" useyou="false" ifcantsee="Facebook-User"></fb:name>

<a href="#" onclick="javascript:FB.Connect.logoutAndRedirect('/index.php'); return false">Logout</a>

$facebook = new Facebook(API_KEY, API_SECRET);
$fb_user = $facebook->require_login();

FB.Connect.init(...);
FB.ensureInit(function() {
FB.Connect.get_status().waitUntilReady( function( status ) {
   switch ( status ) {
     case FB.ConnectState.connected:
        hideLoginButton();
        loggedIn = true;
        break;
     case FB.ConnectState.appNotAuthorized:
     case FB.ConnectState.userNotLoggedIn:
        showLoginButton();
        loggedIn = false;
   }
 });
});