Node.js , Socket.io Error :

[register123]

hallo , ich arbeite gerade an einer Node.js Applikation , nun kriege ich immer wieder den Fehler :
listening on *:3000
C:\xampp\htdocs\nodejs\database.js:27
io.sockets.connected[allClients[xyz]].emit('socketid',allClients[xyz]);
^

TypeError: Cannot read property 'emit' of undefined
at Timeout._onTimeout (C:\xampp\htdocs\nodejs\database.js:27:4 1)
at ontimeout (timers.js:475:11)
at tryOnTimeout (timers.js:310:5)
at Timer.listOnTimeout (timers.js:270:5)

C:\xampp\htdocs\nodejs>node database.js
listening on *:3000
C:\xampp\htdocs\bithunter\nodejs\database.js:28
io.sockets.connected[allClients[xyz]].emit('socketid',allClients[xyz]);
^

TypeError: Cannot read property 'emit' of undefined
at Timeout._onTimeout (C:\xampp\htdocs\nodejs\database.js:28:4 1)
at ontimeout (timers.js:475:11)
at tryOnTimeout (timers.js:310:5)
at Timer.listOnTimeout (timers.js:270:5)
Eigentlich funktioniert alles doch ich hier irgendwie Probleme mit den Verhältnissen der Funktionen , komme aber mit this. auch nicht wirklich weiter ,falls mir jmd. helfen könnte , wäre ich sehr dankbar !

var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
var mysql = require('mysql');
var con = mysql.createConnection({host: "localhost",user: "root",password: "",database: "XXX"}); // MARIADB VERBINDUNDSSYNTAX
con.connect();
//var getusername = setInterval(function ()
//{
//io.on('username',function(msg){console.log(username);});
//console.log("test");
//var format = JSON.stringify(data);
//var queryone = 'SELECT `userbalance` FROM `users` WHERE username = '+format;
//con.query(queryone,function(err, result, fields){var balance = JSON.stringify(result); var balance = balance.replace(/[^0-9]/g,''); console.log(balance)});
//},1000);

var allClients = [];
io.sockets.on('connection', function(socket) {
this.io = io = require('socket.io')(http);
allClients.push(socket.id);
socket.on('disconnect', function() {
var i = allClients.indexOf(socket.id);
allClients.splice(i, 1);
 });
var x = setInterval(function () {
for (xyz = 0  ;xyz < allClients.length ; xyz++)
{
  io.sockets.connected[allClients[xyz]].emit('socketid',allClients[xyz]);
  socket.on('username', function (username,io){io.connected[allClients[xyz]].emit('balance',"you have a account");
   var format = JSON.stringify(username);var queryone = 'SELECT `userbalance` FROM `users` WHERE username = '+format;
  con.query(queryone,function(err, result, fields,socket){var balance = JSON.stringify(result); var balance = balance.replace(/[^0-9]/g,'');});
});
}
},1000);});



// var format = JSON.stringify(data);
// var queryone = 'SELECT `userbalance` FROM `users` WHERE username = '+format;
// con.query(queryone,function(err, result, fields){var balance = JSON.stringify(result); var balance = balance.replace(/[^0-9]/g,'');


http.listen(4041, function(){ console.log('listening on *:3000'); });

[hellbringer]

Warum zweimal require('socket.io')?