1.html

Enter Chat and press enter
<div><input id=input placeholder=you-chat-here /></div>

Chat Output
<div id=box></div>

<script src=http://cdn.pubnub.com/pubnub.min.js></script>
<script>(function(){
var pubnub = PUBNUB.init({publish_key:'demo',subscribe_key:'demo',ssl:true});
var box = PUBNUB.$('box'), input = PUBNUB.$('input'), channel = 'chat';
pubnub.subscribe({
    channel  : channel,
    callback : function(text) { box.innerHTML = (''+text).replace( /[<>]/g, '' ) + '<br>' + box.innerHTML }
});
PUBNUB.bind( 'keyup', input, function(e) {
    (e.keyCode || e.charCode) === 13 && pubnub.publish({
        channel : channel, message : input.value, x : (input.value='')
    })
} )
})()</script>

2.js

// Send a message
pubnub.publish({ channel : 'chat', message : "hello!" })

3.js

// Receive messages
pubnub.subscribe({ channel : 'chat', message : fun })

Build Real-time Chat Apps in 10 Lines of Code

Quickest way to write Real-time Apps on mobile and web.

With PubNub, you can build real-time chat in 10 lines of JavaScript. This is the quickest way to write a real-time chat application on web or mobile.

PubNub’s framework dramatically reduces your coding. Tasks like sending and receiving data take only one function call. And your code instantly updates in web and mobiles apps, for rapid testing.The network infrastructure and scaling is taken care of for you so you spend time building your app, not infrastructure.

See more at: http://www.pubnub.com/blog/build-real-time-chat-10-lines-code/

I just test and really minimum code base. thanks for sharing

This example doesn't require you to specify publish_key or subscribe_key. I am guessing a lot of people around the world must be copy pasting this example to run it. Keeping it running to see if I catch some other peoples' messages as they run it :)

.. this is cool!