Code:

<?php
session_start();

if(isset($_GET['enabled']))
{
 $_SESSION['checker']=true;
}

if(isset($_SESSION['checker']) && $_SESSION['checker'])
{
  //code if javascript is enabled
}
else
{
 echo '<script language="javascript">
  function relocateToScript()
  {
   location.href='index.php?enabled';
  }
  new relocateToScript();
 </script>
';
 //code if javascript is not enabled
}
?>