Mediator implementation.js

var mediator = (function(){
 
    // Storage for topics that can be broadcast or listened to
    var topics = {};
 
    // Subscribe to a topic, supply a callback to be executed
    // when that topic is broadcast to
    var subscribe = function( topic, fn ){
 
        if ( !topics[topic] ){ 
          topics[topic] = [];
        }
 
        topics[topic].push( { context: this, callback: fn } );
 
        return this;
    };
 
    // Publish/broadcast an event to the rest of the application
    var publish = function( topic ){
 
        var args;
 
        if ( !topics[topic] ){
          return false;
        } 
 
        args = Array.prototype.slice.call( arguments, 1 );
        for ( var i = 0, l = topics[topic].length; i < l; i++ ) {
 
            var subscription = topics[topic][i];
            subscription.callback.apply( subscription.context, args );
        }
        return this;
    };
 
    return {
        publish: publish,
        subscribe: subscribe,
        installTo: function( obj ){
            obj.subscribe = subscribe;
            obj.publish = publish;
        }
    };
 
}());