无法使用<a>标签下载文件

function downloadFile(url, filename) {
  fetch(url)
    .then(response => response.blob())
    .then(blob => {
      const link = document.createElement('a');
      link.href = URL.createObjectURL(blob);
      link.download = filename;
      link.click();
      URL.revokeObjectURL(link.href);
    });
}

// 调用示例
downloadFile('http://example.com/file.pdf', 'myfile.pdf');

const express = require('express');
const fs = require('fs');

const app = express();

app.get('/download', (req, res) => {
  const filePath = '/path/to/file.pdf';
  const filename = 'myfile.pdf';

  res.setHeader('Content-Disposition', `attachment; filename="${filename}"`);
  res.setHeader('Content-Type', 'application/pdf');

  fs.createReadStream(filePath).pipe(res);
});

// 启动服务器
app.listen(3000, () => {
  console.log('Server is running on port 3000');
});