Download function realized

接口：类型（blob）
export function getDownload(params) {
  return request({
    url: '/weekly/api/submit/download',
    method: 'get',
    params,
    responseType: 'blob'
  })
}
页面调用的方法： 
   btnDownload() {
      const fileId = this.fileId
      getDownload({ fileId }).then((res) => {
        console.log(res)
        var blob = new Blob([res], {
          type: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document;charset=UTF-8'
        })
        // 解析格式（ type: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document;charset=UTF-8'）
        var filename = this.approverDetail.attachments.fileName
        var a = document.createElement('a')
        var url = window.URL.createObjectURL(blob)
        a.href = url
        a.download = filename
        var body = document.getElementsByTagName('body')[0]
        body.appendChild(a)
        a.click()
        body.removeChild(a)
        window.URL.revokeObjectURL(url)
      })
    },