If you haven't looked at Node.js, you should. Node.js is “evented I/O for V8 javascript”.  With Node.js (and its well documented api) you can write extremely high performance non-blocking event driven network servers in JavaScript.

Here's a simple chat server and client I wrote using Node.js, Faye and the Connect middleware.


app.js (the chat server, run using connect app.js -p 8080):
[sourcecode language="javascript"]
var Faye = require('./lib/faye-node');

var fayeServer = new Faye.NodeAdapter({
mount: '/faye',
timeout: 45
});
var cometServer = {
handle: function(req, res, next){
if (fayeServer.call(req, res)) return;

// Handle non-Faye requests
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello, non-Faye request');
}
};

module.exports = require('./lib/connect').createServer([
{ module: cometServer }
]);
[/sourcecode]
client.html:
[sourcecode language="javascript"]
<html>
<head>
<script src='http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js'></script>
<script type="text/javascript" src="http://localhost:8080/faye.js"></script>
<script type="text/javascript">
$(document).ready(function() {
var client = new Faye.Client('http://localhost:8080/faye');
// receive chat messages
client.subscribe('/messages', function(message) {
var p = $("<div class='chat' style='display:block;'><div class='content'>" + message.text + "</div></div>");
$('#chats').append(p);
$('#chats').scrollTop($('#chats').attr("scrollHeight"));
});
// send message to the chat server
$("#pubmsg").keyup(function(event) {
if (event.keyCode == '13' || event.keyCode == undefined) {
client.publish('/messages', {
text: $("#pubmsg").val()
});
$("#pubmsg").val("").focus();
}
});

$('#pubsend').click(function() {
$('#pubmsg').keyup();
});
});
</script>
<style type="text/css">
#chats {
width: 300px;
height:200px;
border: solid 1px #000;
overflow:auto;
}
</style>
</head>
<body>
<div id="chats"></div>
<input type="text" id="pubmsg" value="" style="width:296px;margin:0px"/> <input type="button" id="pubsend" value="send" />
</body>
</html>
[/sourcecode]