server.js

// server.js
// where your node app starts

// init project
const express = require("express");
const app = express();
const server = require("http").createServer(app);
const mustacheExpress = require("mustache-express");

// socket.io
const io = require("socket.io")(server);

// listen for requests :)
const listener = server.listen(process.env.PORT || 3000, function () {
  console.log("Your app is listening on port " + listener.address().port);
});

// Setup Templating
app.engine("html", mustacheExpress());
app.set("view engine", "html");
app.set("views", __dirname + "/views");

// http://expressjs.com/en/starter/static-files.html
app.use(express.static("public"));

// http://expressjs.com/en/starter/basic-routing.html
app.get("/", function (request, response) {
  response.render("concert", {
    isProduction: process.env.ENVIRONMENT === "production",
  });
});

app.get("/editor", function (request, response) {
  response.render("editor", {
    isProduction: process.env.ENVIRONMENT === "production",
  });
});

app.get("/current_code_debug", function (request, response) {
  response.send({ _code });
});

let _code = undefined;

io.on("connection", function (socket) {
  socket.on("livecode-update", function (code) {
    console.log("CODE UPDATE:", code);
    // save the code here
    _code = code;

    // broadcast the code too
    socket.broadcast.emit("code", _code);
  });

  socket.on("disconnect", function () {
    //
  });
});