json-sockets

a socket optimized for cross-domain use for the web and node. it's easy to use:

var sockets = require('json-sockets');

sockets.listen(9999, function(socket) {
	socket.on('message', function(message) {
		socket.send(message); // echo
	});
});

var socket = sockets.connect('localhost:9999');

socket.send({hello:'world'});
socket.on('message', function(message) {
	console.log(message);
});

A main goal of json-sockets is to be simple, cross-domain, cross-browser and purely native js.
To accomplish this the following transport methods are used:

WebSockets Chrome, Safari, Safari Mobile (fallbacks to CORS on connection timeout)
CORS Firefox 3.5+ [Crome, Safari]
Post-Message + AJAX Internet Explorer 8+, Opera
JSONP Internet Explorer 7- and everybody else

in the browser use the browser.js and a common.js compiler