index.js

const express = require("express")
const app = express()
const http = require("http")
const path = require("path")

const socketIo = require("socket.io")
const server = http.createServer(app)
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("receive-location", { id: socket.id, ...data })
    })
    socket.on("disconnect", function(){
        io.emit("user-disconnected", socket.id)
    })
    console.log("socket connected")
})

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

server.listen(3000)