Under node, io.transports contains duplicates

[mixu]

If you inspect io.transports, you will find that it contains ["websocket", "xhr-polling", "websocket", "xhr-polling"] under Node.

This is because under Node, io.transports contains the names of the supported transports, as added here:
https://github.com/LearnBoost/socket.io-client/blob/master/lib/io.js#L119

but then each transports appends it's name again when loaded, so you get duplicate transport names. I'd assume this is in part why I cannot get Node to emit connect_failed in my tests.

I'm not sure whether io.util.merge() works as intended for the transport array, if that array already contains items. Simple test case (for 0.8.4 via npm):

var obj = { transports: require('socket.io-client').transports };
console.log(obj); // { transports: ['websocket', 'xhr-polling', 'websocket', 'xhr-polling'] }
var result = require('socket.io-client').util.merge(obj, { transports: ['xhr-polling'] });
console.log(result); // { transports: ['xhr-polling', 'xhr-polling', 'websocket', 'xhr-polling'] }

For arrays like transports, it merges by replacing into the existing structure at the given position. util.merge is used to configure the sockets ( https://github.com/LearnBoost/socket.io-client/blob/master/lib/socket.js#L42 )

[3rd-Eden]

Thanks for noticing does it cause you any big issues?

[mixu]

Not this specifically, but I would guess that this issue is related to the reconnect/connect_failed logic (e.g. Socket.redoTransports) not triggering the right events under Node: #311

That one is much more important, since it actually prevents me from verifying that my fallback code works..

[LionelMartin]

Sorry I didn't read that one carefully. Issue 322 is a duplicate of this one.
The result of this issue is quite important as the transport options set are often ignored.
Idea of fix available in issue 322

[plumpNation]

Duplicate of #322