title: Uncaught TypeError: t.querySelectorAll is not a function when initialiazing Embedded Tweets
body: <p>I'm using the Embedded Tweets API from Twitter.
  Everything works great if I have the html markdown from page load.
  It also works great if I use the option to add content later, and load the tweets by ID:</p>
  
  <pre><code>twttr.widgets.load(
    document.getElementById("container")
  );
  </code></pre>
  
  <p>This is in the documentation here: <a href="https://dev.twitter.com/web/javascript/initialization#init" rel="nofollow noreferrer">https://dev.twitter.com/web/javascript/initialization#init</a></p>
  
  <p>But If I try to load the tweets by class name with this:</p>
  
  <pre><code>twttr.widgets.load(
    document.getElementsByClassName("containers")
  );
  </code></pre>
  
  <p>I'm getting this error inside Twitter's widget.js: </p>
  
  <pre><code>Uncaught TypeError: t.querySelectorAll is not a function
  </code></pre>
  
  <p>If I log the group of elements to the console, I have a proper group:</p>
  
  <p><img src="https://i.stack.imgur.com/nHhoK.png" alt="enter image description here"></p>
  
  <p>Am I doing something wrong or is this a bug on Twitter's widget?</p>
  
  <p>Thanks!</p>
  
  <p><strong>EDIT:</strong></p>
  
  <p>As of July 28th 2015, the <code>getElementsByClassName</code> example has been removed from Twitter's documentation thanks to another post I made on the Twitter Dev Forums</p>