在用 excel-export 的时候，出现生成的excel打不开

生成excel

router.get('/excel', function (req, res) {
	var conf ={};
	conf.cols = [
		{caption:'用户ID', type:String},
		{caption:'被约数', type:String},
		{caption:'发约数', type:String}
	];
	conf.rows = [
		['fff','9','1']
	];
	var result = nodeExcel.execute(conf);
	console.log(result); // 这个的输出是乱码，所以excel也是打不开的
	res.setHeader('Content-Type', 'application/vnd.openxmlformats');
	res.setHeader("Content-Disposition", "attachment; filename=" + "Report.xlsx");
	res.end(result, 'binary');
});

求大侠指教