下载文件两种方式： js-file-download、blob

import axios form 'axios'
import qs from 'qs'

// 参数
const body = {
        fileId: this.fileId
 }

get方式下载：( js-file-download )

try {
        axios.get('url', { params: body,  responseType: 'arraybuffer' }).then(res => {
               JsFileDownload(res.data, `测试文件_${new Date().toLocaleString()}.xls`)
        })
 } catch (e) { throw new Error(e) }

post 方式下载：( js-file-download )

      axios({
          url: '/api/system/file/download/by/fileId',
          method: 'post',
          data: qs.stringify(body),
          headers: {
            'Content-Type': 'application/x-www-form-urlencoded;charset=utf-8;'
          },
          responseType: 'arraybuffer'
        }).then(res => {
          JsFileDownload(res.data, `解析错误文件详情_${new Date().toLocaleString()}.xls`)
        })

post 方式下载：( blob / 不用qs序列化参数)

axios({
        url: '/api/system/file/download/by/fileId',
        method: 'post',
        data: body,
        headers: {
          'Content-Type': 'application/x-www-form-urlencoded;charset=utf-8;',
        },
        responseType: 'arraybuffer',
        transformRequest: [function (body) {
             let ret = ''
             for (let it in body) {
               ret += encodeURIComponent(it) + '=' + encodeURIComponent(body[it]) + '&'
              }
               return ret     // 必须返回字符串
           }]
      }).then(res => {
            var blob = new Blob([res.data], {type: 'application/vnd.ms-excel;charset=utf-8'}); //指定格式为vnd.ms-excel
            var downloadElement = document.createElement('a');
            var href = window.URL.createObjectURL(blob);     //创建下载的链接
            downloadElement.href = href
            downloadElement.download = '测试文件.xls';      //下载后文件名
            document.body.appendChild(downloadElement);
            downloadElement.click();    //点击下载
            document.body.removeChild(downloadElement);     //下载完成移除元素
            window.URL.revokeObjectURL(href);     //释放掉blob对象
      })

附：
axios: https://github.com/axios/axios#request-method-aliases