I have this code but it does not work

javascript Code:
  1. <script language="javascript">

  2.  
  3. function script(){

  4.     var today = new Date();

  5.     var weekno = today.getWeek();

  6.     alert(weekno);

  7. }

  8. </script>

  9. </head>

  10.  
  11. <body onload="script();">

  12.  
  13. </body>