index.js

const port = 3000
const express = require('express')
const path = require('path')
const EventEmitter = require('events')
const randomNumberEmitter = new EventEmitter()
var app = express()
app.use(express.static(path.join(__dirname, 'static')))

const bodyParser = require('body-parser')
// parse application/x-www-form-urlencoded
app.use(bodyParser.urlencoded({ extended: false }))

// parse application/json
app.use(bodyParser.json())

var config = {
  defaultEventRate: 100
}

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

io.on('connection', function (socket) {
  socket.on('start', function () {
    console.log('starting')
    randomNumberEmitter.on('newNumber', function (number) {
      // console.log('newNumber', number)
      socket.emit('newNumber', number)
    })
  })
})

server.listen(port, function () {
  // start creating events
  setInterval(function () {
    for (let i = 0; i < config.defaultEventRate; i++) {
      let number = Math.floor(Math.random() * Math.floor(20))
      randomNumberEmitter.emit('newNumber', {number: number, time: Date.now()})
    }
  }, 200)

  console.log('server listetning on port', port)
})