promise-based version of net.createServer

Question

If I create TCP server with net.createServer, I can do conn.on('data' ...) in the connection handler with a callback. Is there version of this that return Promise so can be used with async/await? Or should I use some third-party library for this or roll my own wrapper for conn.on('data' ...) ?

Possible duplicate of [Trigger Promise when an event fires](https://stackoverflow.com/questions/29933088/trigger-promise-when-an-event-fires) — Sven, Feb 10 '18 at 17:37
`await` does not make much sense in the context of TCP sockets. What are you awaiting? A single message? An then? — Tomalak, Feb 10 '18 at 17:43

score 4 · Accepted Answer · answered Feb 10 '18 at 17:38

conn.on('data' ...) can't be replaced with a promise, because it's an event listener, which means that the callback function can be called multiple times. A promise can't be resolved multiple times.

If you're sure that the data event will be emitted only once, you can write a wrapper which will return a promise:

const onData = conn =>
  new Promise((resolve, reject) => {
    conn.on('data', resolve);
    conn.on('error', reject);
  });

promise-based version of net.createServer

1 Answers1