前端下载文件处理文件名称，进行重命名的操作

export const downloadFile = async (url, filename) => {
  const a = document.createElement('a')
  url = url.replace('http:', location.protocol)
  a.href = await toDataUrl(url)
  if (filename.indexOf('.') === -1) {
    const filenameSuffix = url.split('.').pop()
    filename = filename + `.${filenameSuffix}`
  }
  a.download = filename
  document.body.appendChild(a)
  a.click()
  document.body.removeChild(a)
}

export const toDataUrl = url => {
  return fetch(url)
    .then(response => response.blob())
    .then(blob => URL.createObjectURL(blob))
}