前端下载文件流

var blob = new Blob([res.data], {

    type:  "application/octet-stream;charset=UTF-8"

  });

    let elink = document.createElement("a");

    elink.download = ' 文件名称';

    elink.style.display = "none";

    elink.href = URL.createObjectURL(blob);

    document.body.appendChild(elink);

    elink.click();

    URL.revokeObjectURL(blob);

    document.body.removeChild(elink);