index.js

const app = require("express")();
const server = require("http").createServer(app);
const cors = require("cors");
const { METHODS } = require("http");
const { Socket } = require("socket.io");

// SOCKET IO
const io = require("socket.io")(server, {
    cors: {
        origin: "*",
        methods: ["GET", "POST"]
    }
});

app.use(cors());

const PORT = 5000;

app.get('/', (req, res) => {
    res.send("Server is Running");
});

//BACKEND CALL CONNECTION USING SOCKETS

io.on('connection', (socket) => {
    socket.emit('me', socket.id);

    socket.on('disconnect', () => {
        socket.broadcast.emit('callEnded');
    });

    socket.on('callUser', ({ userToCall, signalData, from, name }) => {
        io.to(userToCall).emit('callUser', { signal: signalData, from, name });
    });

    socket.on('answerCall', (data) => {
        io.to(data.to).emit('callAccepted', data.signal);
    });

});

server.listen(PORT, () => console.log('Server is in PORT ' + `${PORT}`));