title: The example code for Facebook Web Login returns an error?
body: <p>I just copy and paste the codes from newest Facebook official documents (<a href="https://developers.facebook.com/docs/facebook-login/login-flow-for-web/v2.4" rel="nofollow noreferrer">Document</a>) (<a href="http://jsfiddle.net/xbnj2cbt/" rel="nofollow noreferrer">JsFiddle</a>):</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
  &lt;title&gt;Facebook Login JavaScript Example&lt;/title&gt;
  &lt;meta charset="UTF-8"&gt;
  &lt;/head&gt;
  &lt;body&gt;
  &lt;script&gt;
    // This is called with the results from from FB.getLoginStatus().
    function statusChangeCallback(response) {
      console.log('statusChangeCallback');
      console.log(response);
      // The response object is returned with a status field that lets the
      // app know the current login status of the person.
      // Full docs on the response object can be found in the documentation
      // for FB.getLoginStatus().
      if (response.status === 'connected') {
        // Logged into your app and Facebook.
        testAPI();
      } 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.  See the onlogin handler attached to it in the sample
    // code below.
    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    : 'v2.2' // use version 2.2
    });
  
    // Now that we've initialized the JavaScript SDK, we call 
    // FB.getLoginStatus().  This function gets the state of the
    // person visiting this page and can return one of three states to
    // the callback you provide.  They can be:
    //
    // 1. Logged into your app ('connected')
    // 2. Logged into Facebook, but not your app ('not_authorized')
    // 3. Not logged into Facebook and can't tell if they are logged into
    //    your app or not.
    //
    // These three cases are handled in the callback function.
  
    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'));
  
    // Here we run a very simple test of the Graph API after login is
    // successful.  See statusChangeCallback() for when this call is made.
    function testAPI() {
      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 + '!';
      });
    }
  &lt;/script&gt;
  
  &lt;!--
    Below we include the Login Button social plugin. This button uses
    the JavaScript SDK to present a graphical Login button that triggers
    the FB.login() function when clicked.
  --&gt;
  
  &lt;fb:login-button scope="public_profile,email" onlogin="checkLoginState();"&gt;
  &lt;/fb:login-button&gt;
  
  &lt;div id="status"&gt;
  &lt;/div&gt;
  
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>When I run <code>testAPI()</code> in my console, the returned user name is <code>undefined</code>:</p>
  
  <p><a href="https://i.stack.imgur.com/JX0ln.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/JX0ln.png" alt="enter image description here"></a></p>
  
  <p>And when I checked the status of the request, it looks like this:</p>
  
  <p><a href="https://i.stack.imgur.com/VKEax.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/VKEax.png" alt="enter image description here"></a>
  <a href="https://i.stack.imgur.com/BaBmN.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/BaBmN.png" alt="enter image description here"></a></p>
  
  <p>It seems an access token is needed, however, I don't know where I should put the access token in the code.</p>
  
  <p>Does anyone have ideas about this?</p>