EventDispatcher JS

addExtensions.js

EventDispatcher.prototype.addExtension = function() {
    for (var i = 0; i < arguments.length; ++i) {
        arguments[i].applyTo(this);
    }
};

Event.js

function Event() {
}

extend(Event.prototype, {
    propagationStopped: false,
    stopPropagation: function() {
        this.propagationStopped = true;
        return this;
    },
    isPropagationStopped: function() {
        return this.propagationStopped;
    }
});

EventDispatcher.js

function EventDispatcher() {
}

extend(EventDispatcher.prototype, {
    listeners: {},
    dispatch: function(eventName, event) {
        var i, events;
        event || (event = new Event);
        events = this.getListeners(eventName);
        for (i = 0; i < events.length; ++i) {
            events[i].call(this, event);
            if (event.isPropagationStopped && event.isPropagationStopped()) {
                break;
            }
        }
        return event;
    },
    on: function(eventName, priority, listener) {
        if (listener === undefined) {
            listener = priority;
            priority = Event.PRIORITY_NORMAL;
        }
        this.listeners[eventName] || (this.listeners[eventName] = {});
        this.listeners[eventName][priority] || (this.listeners[eventName][priority] = []);
        this.listeners[eventName][priority].push(listener);

        return {
            remove: this.remove.bind(this, eventName, listener)
        };
    },
    once: function(eventName, priority, listener) {
        var once;
        if (listener === undefined) {
            listener = priority;
            priority = Event.PRIORITY_NORMAL;
        }
        once = this.on(eventName, priority, function callback() {
            once.remove();
            listener.apply(listener, arguments);
        });
        return once;
    },
    remove: function(eventName, listener) {
        for (var priority in this.listeners[eventName]) {
            var events = this.listeners[eventName], position;
            while ((position = events[priority].indexOf(listener)) > -1) {
                delete events[priority][position];
            }
            if (events[priority].length === 0) {
                delete events[priority];
            }
        }
        return this;
    },
    removeAll: function(eventName) {
        delete this.listeners[eventName];
        return this;
    },
    hasListeners: function(eventName) {
        return this.listeners[eventName] ? true : false;
    },
    getListeners: function(eventName) {
        var result = [], collection = this.listeners;
        if (eventName) {
            collection = {};
            collection[eventName] = this.listeners[eventName];
        }
        for (var name in collection) {
            for (var priority in collection[name]) {
                result = result.concat(collection[name][priority]);
            }
        }
        return result;
    }
});