function download (res) {  //res是后台返回的数据
                            let blob = new Blob([res.data], { type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet' }); //type为所需要下载的文件格式，以xlsx文件为例

                            let url = window.URL.createObjectURL(blob);
                            let fileName = "详情.xlsx";
                            if ("download" in document.createElement("a")) {
                                let a = document.createElement("a");
                                a.href = url;
                                a.download = fileName;
                                a.style.display = "none";
                                document.body.appendChild(a);
                                a.click();
                                URL.revokeObjectURL(a.href);
                                document.body.removeChild(a);
                            } else {
                                navigator.msSaveBlob(blob, fileName);
                            }
                        }

不同格式的文件对应的type ：