simple_events.js

var Events = function(){};

Events.prototype = {
    events: {},
    on: function(eventName, callback, context){
        if(!this.events[eventName]){
            this.events[eventName] = [];
        }
        this.events[eventName].push([callback, context || this]);
    },
    trigger: function(event){
        var i, max, 
            actions = this.events[event],
            args = Array.prototype.slice(arguments, 1);
            
        if(actions){
            for (i=0, max=actions.length; i < max; i++){
                if(false === actions[i][0].call(actions[i][1], args)){
                    break;
                }
            }
        }
    }
};