server.js

var cliento = [];
var hello = [];
var express = require('express'),
  app = express();
var server = app.listen((process.env.PORT || 3000));
var socket = require('socket.io');
var io = socket(server);
var star;
let id = 0;

app.use(express.static('public'));
io.on('connection', newConnection);
console.log("My soket server is running");

//setInterval(createStar, 10000);

function newConnection(socket) {
  console.log('new connection: ' + socket.id);
  socket.on('mouse', mouseMsg);
  socket.on('idle', sendClients);

  function mouseMsg(data) {
    socket.to(data.to).emit('mouse', data);
    //  console.log(data);
  }

  socket.on('idle', sendClients);

  function sendClients() {

    io.clients((error, cliento) => {
      if (error) throw error;
      // Returns an array of client IDs like ["Anw2LatarvGVVXEIAAAD"]
      else {
        //  console.log(cliento);
        hello.splice(0, hello.length);
        for (c of cliento) {
          hello.push(c);
        }
      }
    });
    io.sockets.emit('getClients', hello);

    //var total=io.engine.clientsCount; <--- clients number
  }

  socket.on('invite', (socketId) => { // send invitation
    console.log(socketId);
    socket.to(socketId.whoIWant).emit('gotInvite', socketId.whoAmI);
  });

  socket.on('accepted', (dataAccepted) => {
    socket.to(dataAccepted.whoIWant).emit('isAccepeted', dataAccepted);
  });


  socket.on('star', (dataStar) => {
    if (typeof(star) != undefined) {
      socket.to(dataStar.whoIWant).emit('star2', dataStar.starsNumber);
    }
  });


}
/*
function createStar() {

  star = {
    w: getRandomInt(50, 940 - 100),
    h: getRandomInt(50, 940 - 100),
    starId: id
  }
  id++;
  console.log(star);
}

function getRandomInt(min, max) {
  min = Math.ceil(min);
  max = Math.floor(max);
  return Math.floor(Math.random() * (max - min)) + min; //The maximum is exclusive and the minimum is inclusive
}
*/