title: GreaseMonkey Help with getElementsByClassName
body: <p>I am new to GM and trying to write my first user script. I am trying to get a URL from a facebook comment I was trying to use this.</p>
  
  <pre><code>var e = Array.filter( document.getElementsByClassName('UIStoryAttachment_Title'), function(elem) {
      return elem.nodeName == 'A';
  }
  );
  </code></pre>
  
  <p>But each time I seem to open up a blank page any help on this would be great</p>
  
  <p><img src="https://i.stack.imgur.com/zSDSd.jpg" alt="alt text"></p>