js 异步上传文件

var formData = new FormData($('#form')[0]);
            $.ajax({
                url: 'promote/uploadExcel.do',
                type: 'POST',
                success: function (data) {
                    var data = JSON.parse(data);
                    if (data.errCode == '0000') {
                        layerTool.msg("上传成功");
                        parent.layer.closeAll();
                    }
                },
                error: function (error) {
                    console.log(error)
                },
                data: formData,
                contentType: false,
                processData: false
            });
        }