el. is not a function in joomla

Suppose you are using mootools and jquery in joomla means you will get this error. To clear this error simple use jquery noconflict()

<script type="text/javascript">

  $.noConflict();

  // Code that uses other library's $ can follow here. Replace $ with Jquery text

</script>

Learn jquery from amazon

Simple Technic to get cork from a bottle