handler:function(){
            var cm = grid.getColumnModel();
            var colCount = cm.getColumnCount();
            var columnHeader="";
            for (var i = 1; i < colCount; i++) {
                columnHeader=columnHeader+cm.getColumnHeader(i)+",";
            }
            ds.baseParams['columnHeader'] = columnHeader;
            ds.baseParams['fileName'] = fileName--;
            ds.baseParams['QueryExcel'] ='excelAll';
            flag=true;
            ds.load({
                params:{start:0}
//                callback: function(records, options, success){
//                    flag=false;
//                   var appwindow = window.open (ds.url);
//                      appwindow.focus();
//                }
            });

js这样写有什么问题，，在线求教