如何使用ajax刷新表

<script type=\"text/javascript\">

    function updateTable()
        {
            var xmlhttp;
             var table = document.getElementById(\'theTable\');

            if (window.XMLHttpRequest)
            {// code for IE7+, Firefox, Chrome, Opera, Safari
                xmlhttp=new XMLHttpRequest();
            }

            else
            {// code for IE6, IE5
                xmlhttp=new ActiveXObject(\"Microsoft.XMLHTTP\");
            }

            xmlhttp.onreadystatechange=function()
            {

                if (xmlhttp.readyState==4 && xmlhttp.status==200)
                {
                    document.getElementById(\'theTable\').innerHTML=xmlhttp.responseText;
                }
            }

            xmlhttp.open(???);
            xmlhttp.send();

        }

    //Refresh every 2 seconds
    setInterval( doStuff, 2000 ); 

</script>

        <!-- The actual Table needed to updated -->

    </TABLE>
    <TABLE id=\"theTable\">
     <TH>status</TH> 
     <tr>
      <td><%=status%></td>
     </tr>
    </table>