blob转换成string格式同步调用问题解决分析

content-disposition: attachment;filename=文件名.xlsx
content-type: application/vnd.ms-excel;charset=utf-8

// content-disposition: attachment;filename=文件名.xlsx
const contentDisposition = response.headers['content-disposition']
const _fileName = contentDisposition.split('=')[1]
const fileType = _fileName.substring(_fileName.lastIndexOf('.')); // .xlsx
const fileName = _fileName.substring(0, _fileName.lastIndexOf('.')); // 文件名
if (fileName && fileType) {
  return {
    data: response.data,
    fileName,
    fileType
  }
}

export const downloadFile = (srcData, fileName='下载', fileType='.xls', target='_self') {
  var blob = new Blob([srcData])
  if (window.navigator && window.navigator.msSaveOrOpenBlob) {
    // 兼容IE/Edge
    window.navigator.msSaveOrOpenBlob(blob, fileName + fileType)
  } else {
    var url = window.URL.createObjectURL(blob)
    var a = document.createElement('a')
    a.href = url
    a.target = target
    a.style.display = 'none'
    a.setAttribute('download', fileName + fileType)
    document.body.appendChild(a)
    a.click()
    document.body.removeChild(a)
    window.URL.revokeObjectURL(url) // 释放资源
  }
}
export const blobToString = (blobData) => {
  return new Promise((resolve) => {
    if (blobData instanceof Blob) {
      const reader = new FileReader();
      reader.readAsText(blobData, 'utf-8')
      reader.onload = function () {
        resolve(reader.result || '')
      }
    } else {
      resolve('')
    }
  })
}

// 省略部分代码
async down() {
  try {
    const res = await API();
    const { data, fileName, fileType, code} = res || {}
    if (code === -1) {
      const result = await blobToString(data)
      this.$message.error(result)
      return
    }
    downloadFile(data, fileName, fileType)
  } catch (err) {
    console.log(err)
  }
}