How to download a file into a Buffer in Node.js?

https.get(url, (res) => {
  const data = [];
  res.on('data', (chunk) => {
    data.push(chunk);
  }).on('end', () => {
    let buffer = Buffer.concat(data);
    // Do something with the buffer
  });
}).on('error', (err) => {
  console.log('download error:', err);
});