I am trying to create a gzip stream which I can re-use elsewhere. Gzip works good to compress a stream of data but I wanted to refactor my code so I could seperate concerns. In doing so I ended up with the following. However, I can't utilised the returned stream.

const zlib = require('zlib');

function compress(stream) {
  return new Promise((resolve, reject) => {
    const gzipStream = zlib.createGzip();

    gzipStream.on('end', () => {
      resolve(gzipStream);
    });

    gzipStream.on('error', (e) => {
      reject(e);
    });

    stream.pipe(gzipStream);
  });
}

However I get empty output when I use the returned stream. E.g. I compress a 50mb file filled with 0's, and after using my new function, I get an empty file.

async function handler(req, res) {
  const fileStream = fs.createReadStream("./test_50m");
  const compressedStream = await compress(fileStream);
  
  compressedStream.pipe(fs.createWriteStream("./test_50m_output"));
}

Thanks