Socket.io connection reverts to polling, never fires the 'connection' handler

Question

I'm trying to add socket.io to my existing node.js app on express. I've added the socket.io library in the server-side as follows (directly following http://socket.io/get-started/chat/):

var express = require('express')     , http = require('http')     , path = require('path')     , fs = require('fs');  var app = express(); var http = http.Server(app); var io = require('socket.io')(http);  // Express settings [...] // Express routes [...]  // Socket.io Communication io.on('connection', function(socket) {   console.log('a user connected'); });   // Start server app.listen(config.port, function () {   console.log('Express server listening on port %d in %s mode', config.port, app.get('env')); }); 

Right now, on the front-end I am simply making a connection:

<script src="/socket.io/socket.io.js"></script> <script>   var io = io(); </script> 

But instead of showing "a user connected" in the console, the console logs a continuous stream of polls. I am using the latest version of Chrome on Mac, which supports websockets.

GET /socket.io/?EIO=2&transport=polling&t=1402521519446-91 200 94ms - 6.96kb GET /socket.io/?EIO=2&transport=polling&t=1402521519447-92 200 93ms - 6.96kb GET /socket.io/?EIO=2&transport=polling&t=1402521519485-93 200 53ms - 6.96kb GET /socket.io/?EIO=2&transport=polling&t=1402521519580-94 200 143ms - 6.96kb GET /socket.io/?EIO=2&transport=polling&t=1402521519582-95 200 144ms - 6.96kb GET /socket.io/?EIO=2&transport=polling&t=1402521519633-96 200 40ms - 6.96kb GET /socket.io/?EIO=2&transport=polling&t=1402521519778-97 200 92ms - 6.96kb GET /socket.io/?EIO=2&transport=polling&t=1402521519780-98 200 92ms - 6.96kb GET /socket.io/?EIO=2&transport=polling&t=1402521519818-99 200 36ms - 6.96kb GET /socket.io/?EIO=2&transport=polling&t=1402521519912-100 200 81ms - 6.96kb [etc] 

I must be doing something wrong. I'm pretty new to this, and I'd love to be pointed in the right direction. Let me know if I need to elaborate on any part of this question.

Thanks! - Edward

===========

EDIT:

Here's the express settings I'm currently using. I tried the same steps on a completely new node app and it seemed to work fine, so I'm wondering if any of this might be the issue.

app.configure('development', function(){     app.use(require('connect-livereload')());      // Disable caching of scripts for easier testing     app.use(function noCache(req, res, next) {         if (req.url.indexOf('/scripts/') === 0) {             res.header('Cache-Control', 'no-cache, no-store, must-revalidate');             res.header('Pragma', 'no-cache');             res.header('Expires', 0);         }         next();     });      app.use(express.bodyParser({limit: '50mb'})); // increase limit for audio recordings     app.use(express.static(path.join(config.root, '.tmp')));     app.use(express.static(path.join(config.root, 'app')));     app.use(express.errorHandler());     app.use(express.logger('dev'));      util.logger.add(loggly, {          [...Credentials...]     });     app.set('views', config.root + '/app/views'); }); 

Answer 1

I had the same problem and the way how I solved it was by replacing this

// Start server app.listen(config.port, function () {     console.log('Express server listening on port %d in %s mode', config.port, app.get('env')); }); 

with this:

// Start server http.listen(config.port, function () {     console.log('Express server listening on port %d in %s mode', config.port, app.get('env')); }); 

This post kinda explains why: https://stackoverflow.com/a/17697134/1515130