// This is called with the results from from FB.getLoginStatus().
function statusChangeCallback(response) {

	// The response object is returned with a status field that lets the app 	know 		the current login status of the person.
  if (response.status === 'connected') {
    console.log('Welcome!  Fetching your information.... ');
    FB.api('/me', function(response) {
      console.log('Successful login for: ' + response.name);
      document.getElementById('status').innerHTML =
        'Thanks for logging in, ' + response.name + '!';
    });
  } else if (response.status === 'not_authorized') {
    // The person is logged into Facebook, but not your app.
    document.getElementById('status').innerHTML = 'Please log ' + 'into this app.';
  } else {
    // The person is not logged into Facebook, so we're not sure if they are logged into this app or not.
    document.getElementById('status').innerHTML = 'Please log ' + 'into Facebook.';
  }

}

// This function is called when someone finishes with the Login Button.
function checkLoginState() {
  FB.getLoginStatus(function(response) {
    statusChangeCallback(response);
  });
}

window.fbAsyncInit = function() {
  FB.init({
    appId : '{your-app-id}',
    cookie : true, // enable cookies to allow the server to access the session
    xfbml : true, // parse social plugins on this page
    version : 'v2.1' // use version 2.1
  });

  // Now that we've initialized the JavaScript SDK, we call FB.getLoginStatus(). 
  // This function gets the state of the person visiting this page.
  FB.getLoginStatus(function(response) {
    statusChangeCallback(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'));