title: Iframe ContentWindow
body: <p>When I try to get the contentwindow out of an iframe, using </p>
  
  <pre><code>var contentWindow = document.getElementbyId('iframe').contentWindow 
  </code></pre>
  
  <p>sometimes it returns "Window undefined" because the contentWindow doesn't exist.  I can't seem to run a check for it using </p>
  
  <pre><code>if (contentWindow === unidentified) or if (contentWindow === null)
  </code></pre>
  
  <p>as it just errors out of the code if I try to grab values out of it.  Has anyone else run into this problem and figured out a solution?</p>