jQuery Official Doc.

<link media="screen" type="text/css" href="r/insum/files/static/v2Y/ui.all.css" rel="stylesheet">
<script src="http://www.google.com/jsapi"></script>
<script>
    // Load jQuery
    google.load("jquery", "1.2.6");
</script>
<script src="r/insum/files/static/v2Y/jquery.ui.all.1.6rc2.js"></script>
<script>
    $(function() {
    
        $("#progressbar").progressbar(
            {interval: 2000 
            }
        ); 
        $("#progressbar").progressbar("start");
    
        // send request
        $.post("wwv_flow.show", 
               {p_flow_id:$('#pFlowId').attr("value"), 
                p_flow_step_id:"27", 
                p_instance:$('#pInstance').attr("value"), 
                p_request:""},
               function(data){
                    var startTag = '<apex:ajax>';
                    var endTag = '</apex:ajax>';
                    var start = data.indexOf(startTag);
                    
                    if (start > 0) {
                        data = data.substring(start+startTag.length);
                        var end = data.indexOf(endTag);
                        data = data.substring(0,end);
                    }
                    
                    $("#p27_report_drop td.t4RegionBody").html(data);
                    
                    //Workaround to make the report "pagination" and "order by" work
                    $('#pFlowStepId').attr("value","27");
                    
                    $("#progressbar").progressbar("destroy");
               }
        );
    });
</script>