(Skip to the jsfiddle if you'd like to see a live example)

I made some changes to Mediator.js which were originally going to be in 0.3, but just as I was about to push an update (the update being "assigning predicates to channels"), I decided to to go ahead and implement namespacing. You can now subscribe to things like "application:chat:receiveMessage" directly, or subscribe higher up on "application:chat" to receive everything under the namespace. Callbacks are applied recursively. Subscribing, publishing, and removing all work recursively with namespaces.

It was an interesting engineering challenge to turn "x:y:z" into Channel[x][y][z]; the transformation was pretty simple, but there's still something in the back of my mind shouting that "there's a better way to do this". Right now, it loops through and generates new Channel objects until it runs out of the split string's index, as such:

var namespaceHeirarchy = namespace.split(':');

if(namespaceHeirarchy.length > 0){

  for(var i = 0, j = namespaceHeirarchy.length; i < j; i++){
    if(!channel.HasChannel(namespaceHeirarchy[i])){
      channel.AddChannel(namespaceHeirarchy[i]);
    }

    channel = channel.ReturnChannel(namespaceHeirarchy[i]);
  }
}

Some of the method signatures have been changed so that things make a little more sense; Subscribe now uses (channel, callback, options, context) where it used to use (channel, callback, context, options). It didn't make sense having callback come before options (especially as options are more likely to be used than context.) Options now holds the predicate (if there is one), rather than using the predicate as a channel. And as always, we have no external library dependencies. The minified/gzipped library is up to 580 bytes now, over my goal by 80... version 0.4.1 may be tweaked to get us back under that limit.

An internal change is that Channel is now its own object with AddChannel, AddSubscriber , Remove, Publish, HasChannel commands, which makes it easier to nest channels in channels and tack on callbacks without losing track of context. It's all only used internally within Mediator (and, of course, all tested.)

The latest is up on Github with an updated readme file that explains how to use everything. I've also updated my example on  jsfiddle with the latest method signature changes.