server.js

const net = require("node:net");

const PORT = 4020;
const HOST = "127.0.0.1";

const server = net.createServer();

// an array of client sockets
const clients = [];

server.on("connection", (socket) => {
    console.log("A new connection to the server!");

    const clientId = clients.length + 1;

    // Broadcasting a message to everyone when someone enters the chat room
    clients.map((client) => {
        client.socket.write(`User ${clientId} joined!`);
    });

    socket.write(`id-${clientId}`);

    socket.on("data", (data) => {
        const dataString = data.toString("utf-8");
        const id = dataString.substring(0, dataString.indexOf("-"));
        const message = dataString.substring(dataString.indexOf("-message-") + 9);

        clients.map((client) => {
            client.socket.write(`> User ${id}: ${message}`);
        });
    });

    // Broadcasting a message to everyone when someone leaves the chat room
    socket.on("end", () => {
        clients.map((client) => {
            client.socket.write(`User ${clientId} left!`);
        });
    });

    clients.push({ id: clientId.toString(), socket });
});

server.listen(PORT, HOST, () => {
    console.log("opened server on", server.address());
});