关于javascript:通过后台url来下载文件

import axios from 'axios'
import {getToken} from '@/utils/auth'

const mimeMap = {
  xlsx: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
  zip: 'application/zip'
}

const baseUrl = process.env.VUE_APP_BASE_API
export function downloadExcel(str, type="xlsx", filename) {
  axios({
    method: 'get',
    url: baseUrl + str,
    responseType: 'blob',
    headers: {'Authorization': 'Bearer' + getToken() }
  }).then(res => {resolveBlob(res, mimeMap[type])
  })
}
/**
 * 解析 blob 响应内容并下载
 * @param {*} res blob 响应内容
 * @param {String} mimeType MIME 类型
 */
export function resolveBlob(res, mimeType) {var blob = new Blob([res.data], {type: mimeType});
  // 从 response 的 headers 中获取 filename, 后端 response.setHeader("Content-disposition", "attachment; filename=xxxx.xlsx") 设置的文件名;
  var patt = new RegExp('filename=([^;]+\\.[^\\.;]+);*');
  var contentDisposition = decodeURI(res.headers['content-disposition']);
  var result = patt.exec(contentDisposition);
  var fileName = result[1];
  fileName = fileName.replace(/\"/g,'');
  const ObjectUrl = URL.createObjectURL(blob);

  // 对于 <a> 标签，只有 Firefox 和 Chrome（内核）反对 download 属性
  if ('download' in document.createElement('a')) {const aLink = document.createElement('a');
    aLink.href = ObjectUrl;
    aLink.setAttribute('download', fileName) // 设置下载文件名称
    document.body.appendChild(aLink)
    aLink.click()
    window.URL.revokeObjectURL(ObjectUrl) // 开释 URL 对象
  } else {
    // IE 浏览器兼容办法
    window.navigator.msSaveBlob(blob, fileName)
  }
}

备注：实质还是拿到后盾的文件流数据，而后前端转成二进制文件，通过 a 标签的 download 属性来下载