app.js

const express = require('express');
const app = express();
const path = require('path')

const http = require('http');

const server = http.createServer(app);
const socketio = require('socket.io');
const io = socketio(server)

app.set('view engine', 'ejs');
app.use(express.static(path.join(__dirname, "public")));

io.on("connection", function(socket){
    socket.on("send-location", function(data){
        io.emit("received-location", {id:socket.id, ...data});
    });

    socket.on("disconnect", function(){
        io.emit("user-disconnected", socket.id);
    });
});

app.get("/", function(req, res) {
    res.render("index");
});

server.listen(3000);