title: what is "function(response){}"
body: <p>I was reading the Facebook API when I come across <a href="https://developers.facebook.com/docs/sharing/reference/feed-dialog/v2.5" rel="nofollow">this page</a>, where there is this snippet:</p>
  
  <pre><code>FB.ui({
    method: 'feed',
    link: 'https://developers.facebook.com/docs/',
    caption: 'An example caption',
  }, function(response){});
  </code></pre>
  
  <p>This code confuses me. If my understanding is correct, this is a function call of <code>FB.ui</code>, its first parameter is an object literal. But what is its 2nd parameter, what is this <code>function(response){}</code>? It seems to me this should be a syntax error.</p>