my command repeat with every refresh page in node js - node.js

Question

Im using node js with express framework and socket.io in my project.
when i load test page in browser(with this address: http://localhost:3001/test) every thing is fine and print "a user connected" in server log but when i refresh page again print that message two time and with another refresh print that message three times and with every refresh repeat that message.
whats wrong in my code ?
thanks.
test.js
var express = require('express');
var router = express.Router();
var io = require('../app');
router.get('/', function(req, res, next) {
io.on('connection', function(socket){
console.log('a user connected');
});
res.render('test', { title: 'test' });
});
module.exports = router;
app.js
var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var session = require('express-session')
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var app = express();
var server = require('http').Server(app);
var io = require('socket.io')(server);
server.listen(3001);
module.exports = io;
var index = require('./routes/index');
var users = require('./routes/users');
var test = require('./routes/test');
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'hbs');
// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));
app.use('/', index);
app.use('/users', users);
app.use('/test', test);
// catch 404 and forward to error handler
app.use(function(req, res, next) {
var err = new Error('Not Found');
err.status = 404;
next(err);
});
// error handler
app.use(function(err, req, res, next) {
// set locals, only providing error in development
res.locals.message = err.message;
res.locals.error = req.app.get('env') === 'development' ? err : {};
// render the error page
res.status(err.status || 500);
res.render('error');
});
module.exports = app;

Answer 1

You are adding an additional event handler on every GET / request.
You only need to add the event handler once, outside of a http route. Think of it as the socketio equivalent of a route.
var io = require('socket.io')(server);
io.on('connection', function(socket){
console.log('a user connected');
});
Then in your router, just deal with the http request
router.get('/', function(req, res, next) {
res.render('test', { title: 'test' });
});