响应中的字符串似乎是Base-64编码的（参考小提琴）。您可以使用 fetch（）（或旧版浏览器的 XMLHttpRequest（））对其进行解码：

The string from the response seem to be Base-64 encoded (ref. fiddle). You can decode it using fetch() (or XMLHttpRequest() for older browsers):

fetch("data:application/pdf;base64," + response.data)
  .then(function(resp) {return resp.blob()})
  .then(function(blob) {
    FileSaver.saveAs(blob, 'foo.pdf')
  });