index.js

const app = require("express")();
const server = require("http").createServer(app);
const cors = require("cors");

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

app.use(cors());

const PORT = process.env.PORT || 5000;

app.get('/',(req, res) =>{
    res.send('Server is up and running.');
});

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)
    });

    socket.on("messageUser", ({ name, to, msg, sender }) => {
        io.to(to).emit("recieveMsg", { name, msg, sender });
      });
    
});

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