Checking if browser is in fullscreen
<p>Is there a way to check if a browser is currently in fullscreen mode (after the user pressed f11)?</p>

<p>Something like:</p>

<pre><code>if (window.fullscreen) {
  // it's fullscreen!
}
else {
  // not fs!
}
</code></pre>

<p>Thanks.</p>

<p>Steerpike's answer is pretty good, but my comment:</p>

<blockquote>
  <p>Thanks a lot, but this answer is not
  sufficient for FF. In Chrome I can set
  a small tolerance, but in FF the
  urlbar and tabs takes a while to
  disappear, which means after pressing
  f11, the detected window.innerWidth is
  still too small.</p>
</blockquote>
