I am trying to make a div disappear with javascript. It just doesn't work. What am I doing wrong?

<script src=//code.jquery.com/jquery-1.11.0.min.js></script>

<script type=text/javascript>    

    document.getElementById(des).style.visibility = hidden;    

</script>    



<div id=des>

  Text.

  <a href=>link</a>    

</div>