Very simple FB Login w/javascript+fb sdk

gistfile1.js

// This is called with the results from from FB.getLoginStatus().
      
      // Welcome: I am the Gatekeeper. Are you the Keymaster?
      function theGatekeeper(response) {
        console.log('FB Login object response:');
        console.log(response);
        // FB.getLoginStatus() responds
        if (response.status === 'connected') {
          // logged into FB + permissions OK: You are the Keymaster
          console.log('login OK, running ');
          theKeymaster();
        } else if (response.status === 'not_authorized') {
          // logged into FB + permissions FAIL: You are NOT the Keymaster
          document.getElementById('status').innerHTML = 'Click to grant permissions ' +
            'to App.';
        } else {
          // not logged into FB + permissions UNKNOWN: You are NOT the Keymaster and you DO NOT have the key
          document.getElementById('status').innerHTML = 'Click to login ' +
            'in Facebook.';
        }
      }

      // Check login status. Run the Gatekeeper in response to login button.
      function checkLoginState() {
        FB.getLoginStatus(function(response) {
          theGatekeeper(response);
        });
      }

      // Init FB SDK on load
      window.fbAsyncInit = function() {
      FB.init({
        appId      : '{{app-id}}',
        cookie     : true,  // enable cookies
        xfbml      : true,  // parse social plugins on this page
        version    : 'v2.1' // use version 2.1
      });

        // Providing callbacks for the Gatekeeper via checkLoginState
        FB.getLoginStatus(function(response) {
          theGatekeeper(response);
        });

      };

      // Load the SDK asynchronously
      (function(d, s, id) {
        var js, fjs = d.getElementsByTagName(s)[0];
        if (d.getElementById(id)) return;
        js = d.createElement(s); js.id = id;
        js.src = "//connect.facebook.net/en_US/sdk.js";
        fjs.parentNode.insertBefore(js, fjs);
      }(document, 'script', 'facebook-jssdk'));

      // Prying into FB.api: I am the Keymaster
      function theKeymaster() {
        console.log('FB Login OK');
        FB.api('/me', function(response) {
          console.log('Graph API OK: Welcome, ' + response.name);
        });
      }