os and os version detection in javascript
<blockquote>
  <p><strong>Possible Duplicate:</strong><br>
  <a href="http://stackoverflow.com/questions/9514179/how-to-find-the-operating-system-version-using-javascript">How to find the operating system version using JavaScript</a>  </p>
</blockquote>



<p>how i can detect that my visitor using which os and os version in javascrtip . for example windows vista or seven or Xp and linux too . </p>
