Facebook Login

gistfile1.html

<div id="fb-root"></div>
<script src="https://connect.facebook.net/en_US/all.js"></script>
<script type="text/javascript" charset="utf-8">
	FB.init({
    	appId  : 'APP ID HERE',
    	status : true, 
    	cookie : true, 
    	xfbml  : true,
  	});
</script>
<script>
	// Call this function once the user clicks a button
	// Don't auto call it!!
	FB.getLoginStatus(function(response) {
	  if (response.session) {
		  // Already logged in
	  } else {
        FB.login(function(response) {
		  if (response.authResponse) {
		     // Logged in
		   } else {
		   	// Failed
		   }
		},{ scope:'' });
	  }
	});
</script>