<td>
                        <select name="type" id="type_id">
                            <option value="">请选择</option>                         
                            <volist name="type" id="val">
                               <option value="{$val["id"]}">{$val["typename"]}</option>
                            </volist>                         
                        </select>
                    </td>
                   <script>
                        //找下拉框的值 
                        type_id: $.trim($('#type_id option:selected') .val()),
                   </script>