app.js

var express = require('express');
var app = express();
var serv = require('http').Server(app);

app.get('/',function(req,res){
  res.sendFile(__dirname + '/client/index.html');
});

app.use('/client',express.static(__dirname + '/client'));

serv.listen(2000);
console.log("Server started.");

var SOCKET_LIST = {};
var PLAYER_LIST = {};

var tickCount = 0;
var ticksPerFrame = 3;
var runTicsPerFrame = 1;
var walkTicsPerFrame = 3;

var numberOfFrames = 4;

var upVal = 210;
var downVal = 0;
var leftVal = 70;
var rightVal = 140;

var Player = function(id){
  var self = {
    x:0,
    y:20,
    id:id,
    pic:"client/img/spriteshurt.png",
    direction:0,
    frameIndex:0,
    number: "" + Math.floor(10 * Math.random()),
    pressingRight:false,
    pressingLeft:false,
    pressingUp:false,
    pressingDown:false,
    run:false,
    runSpeed:15,
    walkSpeed:7,
    actualSpeed:7,
  }
  self.updatePosition = function() {
    if(self.pressingRight){
      self.x +=self.actualSpeed;
    }
    if(self.pressingLeft){
      self.x -=self.actualSpeed;
    }
    if(self.pressingUp){
      self.y -=self.actualSpeed;
    }
    if(self.pressingDown){
      self.y +=self.actualSpeed;
    }
    if(self.run){
      self.actualSpeed = self.runSpeed;
      ticksPerFrame = runTicsPerFrame;
    }else{
      self.actualSpeed = self.walkSpeed;
      ticksPerFrame = walkTicsPerFrame;
    }
    
  }
  self.updateDirection = function() {
    if(self.pressingUp || self.pressingDown || self.pressingLeft || self.pressingRight){
      if(self.pressingUp){
        self.direction = upVal;
      }else if(self.pressingDown){
        self.direction = downVal;
      }else if(self.pressingLeft){
        self.direction = leftVal;
      }else if(self.pressingRight){
        self.direction = rightVal;
      }
      if (tickCount > ticksPerFrame) {
        tickCount = 0;
        if(self.frameIndex < numberOfFrames - 1){
          self.frameIndex += 1; 
        }else{
          self.frameIndex = 0; 
        }
      }
    }
  }
  return self;
}

var io = require('socket.io') (serv,{});
io.sockets.on('connection', function(socket){
  socket.id = Math.random();
  socket.x = 0;
  socket.y = 0;
  socket.number = "" + Math.floor(10 * Math.random());
  SOCKET_LIST[socket.id] = socket;
  var player = Player(socket.id);
  PLAYER_LIST[socket.id] = player;

  socket.on('disconnect', function(){
    delete SOCKET_LIST[socket.id];
    delete PLAYER_LIST[socket.id];
  });

  socket.on('newColor', function(data){
    player.pic = data.pic;
  });

  socket.on('keyPress', function(data){
    if(data.inputId === 'left'){
      player.pressingLeft = data.state;
    }else if (data.inputId === 'right'){
      player.pressingRight = data.state;
    }else if (data.inputId === 'up'){
      player.pressingUp = data.state;
    }else if (data.inputId === 'down'){
      player.pressingDown = data.state;
    }
    if (data.inputId === 'run'){
      player.run = data.state;
    }
  });
});

setInterval(function(){
  var pack = [];
  tickCount += 1;
  for(var i in PLAYER_LIST){
    var player = PLAYER_LIST[i];
    player.updatePosition();
    player.updateDirection();
    pack.push({
      x:player.x,
      y:player.y,
      pic:player.pic,
      frameIndex:player.frameIndex,
      direction:player.direction,
      number:player.number
    });
  }
  for(var i in SOCKET_LIST){
    var socket = SOCKET_LIST[i];
    socket.emit('newPosition',pack);
  }
},1000/25);