Event, EventTarget, EventListener

gistfile1.txt

var Event = function(type, target, sender, payload){
    this.type = type;
    this.target = target;
    this.sender = sender;
    this.payload = payload;
};

var EventTarget = function(){
    this.eventListeners = [];
};

EventTarget.prototype.listen = function(type, listener){
    var self = this;
    var wrapper = function(e) {
        if (typeof listener.handleEvent != 'undefined') {
            listener.handleEvent(e);
        } else {
            listener.call(self, e);
        }
    };
    console.log(this);
    this.eventListeners.push({
        object: this,
        type: type,
        listener: listener,
        wrapper: wrapper
    });
};

EventTarget.prototype.unlisten = function(type, listener){
    var eventListeners = this.eventListeners;
    var counter = 0;
    while(counter < eventListeners.length){
        var eventListener = eventListeners[counter];
        if (eventListener.object == this &&
            eventListener.type == type &&
            eventListener.listener == listener){
            eventListeners.splice(counter, 1);
            break;
        }
        ++counter;
    }
};

EventTarget.prototype.dispatch = function(type, sender, payload){
    var eventListeners = this.eventListeners;
    var counter = 0;
    while(counter < eventListeners.length){
        var eventListener = eventListeners[counter];
        if (eventListener.object == this &&
            eventListener.type == type){
            if(type instanceof Event){
                type.target = this;
                type.sender = sender;
                type.payload = payload;
                eventListener.wrapper(type);
            } else {
                eventListener.wrapper(new Event(type, this, sender, payload));
            }
        }
        ++counter;
    }
};

var EventListener = function(callback){
    this.callback = callback;
};

EventListener.prototype.handleEvent = function(event){
    this.callback(event);
};