Socket io dynamic rooms

index.js

const express = require("express");
const { createServer } = require("http");
const { Server } = require("socket.io");

const app = express();
const httpServer = createServer(app);

const io = new Server(httpServer, {
    cors: {
        origin: "*",
        methods: "*",
        credentials: true
    },
    allowEIO3: true
});

app.get('/', (req, res) => {
    res.send('Hello World!')
})

io.on("connection", (socket) => {
    var chatId = socket.handshake.query.chatId;

    socket.join(chatId);
    socket.on("message", (msg) => {
        socket.to(chatId).emit("message", msg);
    });

    socket.on("disconnect", (reason) => {
        console.log(reason);
    });

    socket.on("leave", () => {
        socket.leave(chatId);
        socket.disconnect();
    });
});

httpServer.listen(3000);