app.js

const express = require("express");
const socketio = require("socket.io");
const peer = require("simple-peer");
const http = require("http");
const cors = require("cors");

const app = express();
const server = http.createServer(app);
const path = require("path");
const io = socketio(server);

app.use(cors());
app.use(express.static(path.join(__dirname, "/public")));

const port = process.env.PORT || 3000;
// 

let clients = 0;
io.on("connection", socket => {
    socket.on("permission_success", () => {
        if (clients < 2) {
            if (clients == 1) {
                console.log(clients);
                socket.emit("makePeer");
            }
        } else {
            socket.emit("sessionActive");
            console.log("err");
        }
        clients++;
    });
    socket.on("offer", offer => {
        socket.broadcast.emit("backReply", offer);
    });
    socket.on("Answer", data => {
        socket.broadcast.emit("backanswer", data);
    });
    socket.on("disconnect", () => {
        if (clients > 0) {
            clients -= 1;
        }
    });
});

server.listen(port);