[WebSocketServer] Allow to extend the original WebSocket class

[vansergen]

@lpinca What do you think about adding this feature?

[lpinca]

I'm not very happy with it. Are there big advantages over monkey patching the WebSocket class directly?

const WebSocket = require('ws');

Object.defineProperty(WebSocket.prototype, 'custom_field', {
  get() {
    return '123';
  }
});

[vansergen]

Are there big advantages over monkey patching the WebSocket class directly?

I do believe so. It would give more flexibility in terms of accessing the
original methods while overwriting them

class CustomWebSocket extends WebSocket {
  #sent;
  #created_at;
  constructor(...params) {
    super(...params);
    this.#sent = 0;
    this.#created_at = new Date();
  }
  get sent() {
    return this.#sent;
  }
  get created_at() {
    return new Date(this.#created_at);
  }
  send(...params) {
    this.#sent++;
    super.send(...params);
  }
}

in the same manner as the node:http module does

import { IncomingMessage, ServerResponse, createServer } from 'node:http';
class CustomIncomingMessage extends IncomingMessage {}
class CustomServerResponse extends ServerResponse {}
createServer({
  IncomingMessage: CustomIncomingMessage,
  ServerResponse: CustomServerResponse
}).on('request', (request, response) => {
  console.log(request instanceof CustomIncomingMessage);
  console.log(response instanceof CustomServerResponse);
});

In this way one can modify WebSocket classes per server (without modifying the original class)

import { createServer } from 'http';
import { parse } from 'url';
import { WebSocketServer, WebSocket } from 'ws';

class WebSocket1 extends WebSocket {}
class WebSocket2 extends WebSocket {}

const server = createServer();
const wss1 = new WebSocketServer({ WebSocket: WebSocket1, noServer: true });
const wss2 = new WebSocketServer({ WebSocket: WebSocket2, noServer: true });
const wss3 = new WebSocketServer({ WebSocket, noServer: true });

wss1.on('connection', function connection(ws) {
  // console.log(ws instanceof WebSocket1)
});
wss2.on('connection', function connection(ws) {
  // console.log(ws instanceof WebSocket2)
});
wss3.on('connection', function connection(ws) {
  // console.log(ws instanceof WebSocket)
});

server.on('upgrade', function upgrade(request, socket, head) {
  const { pathname } = parse(request.url);
  if (pathname === '/foo') {
    wss1.handleUpgrade(request, socket, head, function done(ws) {
      wss1.emit('connection', ws, request);
    });
  } else if (pathname === '/bar') {
    wss2.handleUpgrade(request, socket, head, function done(ws) {
      wss2.emit('connection', ws, request);
    });
  } else {
    wss3.handleUpgrade(request, socket, head, function done(ws) {
      wss3.emit('connection', ws, request);
    });
  }
});
server.listen(8080);

[lpinca]

Hmm, ok. It might break if the class does not extend WebSocket and I do not like to keep adding options but it is reasonable.

[lpinca]

Thank you.