easyui 带参数的datagride

 <table id="tt" style="width:100%;height:355px"
                   url="../aowei/Handler/HandlerProjectTrackingList.ashx?ProTrackFlag=Detail"

 title="跟踪
增加" iconCls="icon-edit"    singleSelect="true" idField="itemid" fitColumns="true" striped="true" >
                    <thead>
                        <tr>
                            <th field="ProTrackTime" width="60"align="center">时间th>
                            <th field="ProTrackName" width="80" align="center">姓名th>
                            <th field="ProTrackWay" width="80" align="center" >方式th>
                            <th field="ProTrackRemark" width="180"align="center" >备注th>
                            <th field="ProTrackOpeation" width="190" align="center" >操作th>
                        tr>
                    thead>
                table>

js