Window.fetch() を使用してファイルをダウンロードし、承認を処理する方法は?

.then((response) => {
  // Convert the response to a blob.
  return response.blob();
})
.then((blob) => {
  // Create a URL for the downloaded file.
  const fileURL = URL.createObjectURL(blob);

  // Navigate to the file URL to start downloading the file.
  window.location.assign(fileURL);
});

const url ='http://sample.example.file.doc'
const authHeader ="Bearer 6Q************" 

const options = {
  headers: {
    Authorization: authHeader
  }
};
 fetch(url, options)
  .then( res => res.blob() )
  .then( blob => {
    var file = window.URL.createObjectURL(blob);
    window.location.assign(file);
  });