I am wish to accomplish exactly the same factor. I am not concerned about men and women without js though, however the facebook-js-files loads very slow which slows lower my whole site. Facebook does not work without js and so i guess everybody who wish to login with facebook in your site supports js.
But towards the question. Within the PHP-lib there's one way known as get_login_url which you can use to obtain a sign-in-url for the application.
$connectUrl = $fb->get_login_url("http://www.yoursite.com/loggedin.php",0);
So that you can build your own connect-button that links to that particular url. When the user signed in facebook will redirect him to the url you specify. When the user has already been online on facebook he'll be rerouted back immediately.
Facebook works perfectly fine without js. It functions type of much like twitter's oauth process. take a look at facebook's mobile api.
to login utilizing a PHP varible:
$url_accept is how to transmit the consumer when they accept the login and
$url_cancel when they decline.
$facebook_login_url = 'http://m.facebook.com/tos.php?api_key='.$FACEBOOK_API_KEY.'&v=1.0&next='.$url_accept.'&cancel='.$url_cancel;