Visibility.js - How to usefall back?
<p>I have looked for a solution on How to check active tab in javascript/jquery and I found this post.</p>

<p><a href="http://stackoverflow.com/questions/12489986/how-to-check-active-tab-in-javascript-jsquery">How to check active tab in javascript/jsquery?</a></p>

<p>I tried using the plugin at <a href="https://github.com/ai/visibility.js" rel="nofollow">https://github.com/ai/visibility.js</a> and it works!</p>

<p>I am currently availing of the CDN minified version for my pages.</p>

<p>However some things is bugging me. Is the fallback plugin included in the minified version? Do I need to do something to use the fallback? Or does it work behind the scenes?</p>

<p>EDIT: This is the paragraph that confused me.</p>

<blockquote>
  <p>In most cases you don’t need to check whether the Page Visibility API
  is actually supported in the browser as, if it does not, the library
  will just assume that the page is visible all the time, and your logic
  will still work correctly, albeit less effective in some cases.</p>
</blockquote>

<p>So it is saying that we don't need to check but if it is not supported, just assume that the page is visible all the time? How is that a fallback?</p>
