Use socket.io with Kraken.js

Question

Use socket.io with Kraken.js

705 Views Asked by jbltx At 16 May 2025 at 12:35

I have difficulties to work with socket.io, I thought my project used modules which could enter in confilct with socket.io, so I started a new KrakenJs project, and installed just socket.io.

As the examples found in the official socket.io website, I tried this :

//index.js
'use strict';


var kraken = require('kraken-js'),
    app = require('express')(),
    server = require('http').Server(app),
    io = require('socket.io')(server),
    options = {
        onconfig: function (config, next) {
            //any config setup/overrides here
            next(null, config);
        }
    },
    port = process.env.PORT || 8000;


app.use(kraken(options));

io.on('connection', function(socket){
  console.log('a user connected');
});


app.listen(port, function (err) {
    console.log('[%s] Listening on http://localhost:%d', app.settings.env, port);
});

My route controller :

'use strict';
module.exports = function (router) {
    router.get('/', function (req, res) {
        res.sendfile('./public/templates/index.html');
    });
};

And the html page (the same as the example in the website) :

<!doctype html>
<html>
  <head>
    <title>Socket.IO chat</title>
    <style>
      * { margin: 0; padding: 0; box-sizing: border-box; }
      body { font: 13px Helvetica, Arial; }
      form { background: #000; padding: 3px; position: fixed; bottom: 0; width: 100%; }
      form input { border: 0; padding: 10px; width: 90%; margin-right: .5%; }
      form button { width: 9%; background: rgb(130, 224, 255); border: none; padding: 10px; }
      #messages { list-style-type: none; margin: 0; padding: 0; }
      #messages li { padding: 5px 10px; }
      #messages li:nth-child(odd) { background: #eee; }
    </style>
  </head>
  <body>
    <ul id="messages"></ul>
    <form action="">
      <input id="m" autocomplete="off" /><button>Send</button>
    </form>
   <script src="/socket.io/socket.io.js"></script>
  <script>
    var socket = io();
  </script>
  </body>

</html>

With that code, I have the same error than in my other kraken app... So I decided to test a simple node app without kraken framework, and works fine.

Here's the error which appears with krakenJs :

enter image description here

Where does it come from ? I also test with and without requireJs, but doesn't affect...

EDIT : I saw the error is visible when I enter the client-side script before calling require.js :

<script src="/socket.io/socket.io.js"></script>
<script>
  var socket = io();
</script>
<script data-main="/js/app" src="/components/requirejs/require.js"></script>

And if I put script after :

<script data-main="/js/app" src="/components/requirejs/require.js"></script>
<script src="/socket.io/socket.io.js"></script>
<script>
  var socket = io();
</script>

...there's no errors, but the script is not used (no "connected" message in the console).

Any idea ?

Original Q&A

There are 2 best solutions below

Nisanth Sojan On 27 March 2015 at 06:35

You can try this

app.listen(process.env.PORT, function () {
    console.info('Server listening on http://localhost:%d', this.address().port);
    io = require('socket.io')(this);
});

and give the connection functions at start event function

app.on('start', function () {
    console.info('Application ready to serve requests.');
    console.info('Environment: %s', app.kraken.get('env:env'));

    io.on('connection', function (socket) {
        console.log('io connection');
        socket.emit('news', {hello: 'world'});
        socket.on('my other event', function (data) {
            console.log(data);
        });
    });

});

**jbltx** · Accepted Answer

I finally found what was the problem.

In fact, socket.io has to initialize its program on the server to use inside it. But when you use :

var server = require('http').Server(app),
    io = require('socket.io')(server);

You are using ther server defined by the server variable. So you have to use the listen() method on this variable.

server.listen(8080);

But, by using this variable, I don't think Kraken will be well used in the application. Unfortunately, I didn't find any possibilities to use directly the app variable for listen() method.

Use socket.io with Kraken.js

There are 2 best solutions below

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