server.js

//Lerp module for node
var lerp = require('lerp');
//Grid size
var mapSize = 2035;
//Players + Bots IO (input/output)
var players = [];
var botsIO = [];
var food = [];
var foodCount = 100;
var botCount = 5;

//Replacemet for requestAnimationFrame() AKA REPEAT FUNCTION!
setInterval(tick, 30);

//Constrain function
function constrain(num, min, max) {
  if (num <= min) {
    return min;
  } else if (num >= max) {
    return max;
  } else {
    return num;
  }
}

//Random function in a range
function random(min, max) {
  return Math.random() * (max - min) + min;
}

//Distance between two points 
function dist(x, y, x0, y0) {
  return Math.sqrt((x -= x0) * x + (y -= y0) * y);
}

//Player Info Constructor
function Player(id, x, y, size, attack) {
  this.id = id;
  this.x = x;
  this.y = y;
  this.size = size;
  this.attack = attack;
}
//Food
function Food(size) {
  this.x = Math.floor(random(2, 2000));
  this.y = Math.floor(random(2, 2000));
  this.colorNum = Math.floor(random(1, 8));
  this.size = size;
}
//Server Side Bots Constructor
function Bots() {
  this.x = Math.random() * 2035;
  this.y = Math.random() * 2035;
  this.a = 0;
  this.speedx = random(1, 2);
  this.speedy = random(1, 2);
  this.dirx = 0;
  this.diry = 0;
  this.VK = false;
  this.colNum = Math.floor(random(0, 7));

  var R = 60;
  this.field = R + 10;
  this.fieldPlayer = R + 40;

  this.knockback = 20;
  this.attack = Math.floor(random(1, 3));
  this.health = 2;

  this.eat = function (posx, posy) {

    //Food part!
    var d = dist(this.x, this.y, posx, posy);
    var gapX = posx - this.x;
    var gapY = posy - this.y;
    var nX = this.x + gapX;
    var nY = this.y + gapY;
    if (d < this.field) {
      this.VK = true;
      var newposx = nX;
      var newposy = nY;
      this.x = lerp(this.x, newposx, 0.02);
      this.y = lerp(this.y, newposy, 0.02);
      if (this.VK === true) {
        var directionX = gapX;
        var directionY = gapY;

        this.dirx = lerp(this.dirx, directionX, 0.005);
        this.diry = lerp(this.diry, directionY, 0.005);

        this.speedx = this.dirx;
        this.speedy = this.diry;
        this.VK = false;
      }
      if (d < 5 + R / 2) {
        return true;
      } else {
        return false;
      }
    }
  }
  this.playerInterract = function () {
    //Player part!
    for (var u = 0; u < players.length; u++) {

      var ds = dist(this.x, this.y, players[u].x, players[u].y);

      if (ds < this.fieldPlayer) {
        //this.x = lerp(this.x, players[u].x, 0.05);
        //this.y = lerp(this.y, players[u].y, 0.05);

        if (ds < players[u].size / 2 + R / 2) {
          var dy = players[u].y - this.y;

          this.x += 10;
          if (players[u].x >= this.x) {
            var a = dy / ds;
            var newdis = ds * 2;
            this.y -= newdis * Math.sin(a);
            this.x -= newdis * Math.cos(a);
            this.health -= players[u].attack;
          }
          if (players[u].x <= this.x) {
            var a1 = dy / -ds;
            var newdis1 = ds * 2;
            this.y += newdis1 * Math.sin(a1);
            this.x += newdis1 * Math.cos(a1);
            this.health -= players[u].attack;
          }

        }
      }
    }
  }

  //Bot movement + constrains
  this.interact = function () {
    if (this.VK === false) {
      this.x += this.speedx;
      this.y += this.speedy;
    }
    this.x = constrain(this.x, 0, mapSize);
    this.y = constrain(this.y, 0, mapSize);

    if (this.x === 2035) {
      this.speedx = -this.speedx;
    } else if (this.y === 2035) {
      this.speedy = -this.speedy;
    } else if (this.x === 0) {
      this.speedx = -this.speedx;
    } else if (this.y === 0) {
      this.speedy = -this.speedy;
    }
  }

}

//Creating Bots from a templete (Constructor!)
for (var n = 0; n < botCount; n++) {
  botsIO[n] = new Bots();
  //console.log("Theres are " + botsIO[n].x + " " + botsIO[n].y + " here!");
}
//Creation food and others
for (var v = 0; v <= foodCount; v++) {
  food[v] = new Food(20);
  // console.log(food[v]);
}

//**********************************************************************
//Repeatable function (Uses setInterval() )
function tick() {
  //Ако храната намали създай нова.
  if (food.length < foodCount) {
    var randomizer = Math.floor(random(1, 20));
    //   console.log(randomizer);   
    if (randomizer === 11) {
      var newf = new Food(20);
      food.push(newf);
    }
  }
  for (var p = botsIO.length - 1; p >= 0; p--) {
    //console.log(botsIO[0].x);
    botsIO[p].interact();
    botsIO[p].eat();
    botsIO[p].playerInterract();

    if (botsIO[p].health <= 0) {
      botsIO.splice(p, 1);
    }
  }
  for (var e = players.length - 1; e >= 0; e--) {
    for (var m = food.length - 1; m >= 0; m--) {
      var dis = dist(players[e].x, players[e].y, food[m].x, food[m].y);
      if (dis < 5 + players[e].size / 2) {
        food.splice(m, 1);
      }
    }
  }

  for (var j = botsIO.length - 1; j >= 0; j--) {
    for (var o = food.length - 1; o >= 0; o--) {
      if (botsIO[j].eat(food[o].x, food[o].y)) {
        food.splice(o, 1);
      }
    }
  }
  if (botsIO.length < botCount) {
    ;
    botsIO.push(new Bots());
  }
}

// Using express: http://expressjs.com/
var express = require('express');
// Create the app
var app = express();

// Set up the server
// process.env.PORT is related to deploying on heroku
var server = app.listen(process.env.PORT || 3000, listen);

// This call back just tells us that the server has started
function listen() {
  var host = server.address().address;
  var port = server.address().port;
  console.log('Example app listening at http://' + host + ':' + port);
}

app.use(express.static('public'));


// WebSocket Portion
// WebSockets work with the HTTP server
var io = require('socket.io')(server);

setInterval(heartbeat, 20);


function heartbeat() {
  io.sockets.emit('heartbeat', players);
  if (players.length > 0) {
    //console.log("Emiting " + players[0].hitUp);
  }
  io.sockets.emit('bots', botsIO);
  io.sockets.emit('food', food);
}

// Register a callback function to run when we have an individual connection
// This is run for each individual user that connects
io.sockets.on('connection',
  // We are given a websocket object in our function
  function (socket) {

    console.log("We have a new client: " + socket.id);


    socket.on('start',
      function (data) {
        console.log(socket.id + " " + data.x + " " + data.y + " " + data.size + " " + data.attack);
        var player = new Player(socket.id, data.x, data.y, data.size, data.attack);
        players.push(player);

      }
    );

    socket.on('update',
      function (data) {
        //console.log(socket.id + " " + data.x + " " + data.y + " " + data.size + " " + data.attack);
        var player;
        for (var i = 0; i < players.length; i++) {
          if (socket.id == players[i].id) {
            player = players[i];
          }
        }
        player.x = data.x;
        player.y = data.y;
        player.size = data.size;
        player.attack = data.attack;
      }
    );

    socket.on('disconnect', function () {
      console.log("Client has disconnected");
    });
  }
);