Node.js-14-Cookbook/Chapter04/websocket-server/server.js

const WebSocket = require("ws");

const WebSocketServer = new WebSocket.Server({
  port: 3000,
});

WebSocketServer.on("connection", (socket) => {
  socket.on("message", (msg) => {
    console.log("Received:", msg);
    if (msg === "Hello") socket.send("World!");
  });
});