title: return value of XMLHttpRequest is not same as manually observing the website
body: <p>As the title says - I'm not able to retrieve the same data as what I am seeing. </p>
  
  <p>I'm trying to parse/load an external website using <code>XMLHttpRequest</code> (just checking if a few values exists). When I observe the website using Chrome F12 "Elements" tab part of the html looks as following:</p>
  
  <pre><code>&lt;li class="mail"&gt;
    &lt;a href="my-stuff"&gt;My stuff&lt;span class="notification"&gt;New&lt;/span&gt;&lt;/a&gt;
  &lt;/li&gt;
  </code></pre>
  
  <p>If I right click the browser and press "View source" I will instead see this:</p>
  
  <pre><code>&lt;li class="mail"&gt;
    &lt;a href="my-stuff"&gt;My stuff&lt;/a&gt;
  &lt;/li&gt;
  </code></pre>
  
  <p>Note the lack of the <code>Span</code>-element. This is also the same as what is retrieved by the <code>XMLHttpRequest</code>.</p>
  
  <p>Why is this and is there some way to access the first <code>HTML</code>-snippet? Since that's the only thing I'm trying to access here. I'm guessing it's created after page load or something (via javascript), but how can I access that instead?</p>
  
  <p>Thank you!</p>
  
  <p>(I can't provide you with the webpage I'm testing this on)</p>
  
  <p>EDIT: I'm doing this for a Chrome extension. Is there any way to load a page in the background (not show it) and wait for all javascripts to execute on the page and then get the "final" generated HTML?</p>