server.js

const express = require("express");
const ServerSocket = require("ws").Server;

const PORT = 8080;

const server = express().listen(PORT, () =>
  console.log(`Server running on port ${PORT}`),
);

const wss = new ServerSocket({ server });

// `ws` is Websocket sent by client (Actually, it's the server-side Websocket instance representing the connection to that client, it's not "real" Websocket client)
// `req` is HTTP request object sent by client
wss.on("connection", (ws, req) => {
  console.log("[Client connected]");

  console.log("Req", req.headers);

  ws.id = req.headers["sec-websocket-key"].substring(0, 8);
  ws.send(`[Client ${ws.id} is connected]`);

  // Add event listener for message event
  ws.on("message", (data) => {
    console.log(`[message from client: ${data}]`);

    let clients = wss.clients;

    console.log(wss.clients);

    clients.forEach((client) => {
      client.send("[Broadcast] [Get message from server]");
    });
  });

  ws.on("close", () => {
    console.log("[Client disconnected]");
  });
});