server.js

const express = require("express");
const app = express();
const server = require("http").Server(app);
const io = require("socket.io")(server);
const path = require("path");

app.use(express.static("public"));

app.get("/play", function (req, res) {
    res.sendFile(path.join(__dirname + '/public/playerclient/playerclient.html'))
});

app.get("/quizmaster", function (req, res) {
    res.sendFile(path.join(__dirname + '/public/masterclient/masterclient.html'))
});

io.on("connection", socket => {
    let referer = socket.handshake.headers.referer;
    if (referer.endsWith("play")) {
        socket.join("players");
    };

    socket.on("send-question", questionData => {
        io.in("players").emit("multiple-choice", questionData);
    });

    socket.on("next-answer", function(){
        io.in("players").emit("next-answer");
    });

    socket.on("reveal-answer", correctAnswerIndex => {
        io.in("players").emit("reveal-answer", correctAnswerIndex);
    });

    socket.on("destroy-question", function(){
        io.in("players").emit("destroy-question");
    });

});

server.listen(80, "0.0.0.0", ()  => console.log("listening..."));