EventGroup.js

var EventGroup = function(target) {
    this.target = target || window;
    this.handlers = {};
    this.doPreventDefault = true;
    this.doStopPropagation = true;
    var self = this;
    this.delegate = function(e) {
        if (!e) e = window.event;
        if (!e.target) e.target = e.srcElement;
        if (!e.stopPropatation) e.stopPropagation = function() {this.cancelBubble = true};
        if (!e.preventDefault) e.preventDefault = function() {this.returnValue = false};
        if (this.doPreventDefault) e.preventDefault();
        if (this.doStopPropagation) e.stopPropagation();
        var handlers = self.handlers[e.type];
        if (handlers) {
            for (var i = 0; i < handlers.length; i++) handlers[i].call(self, e);
        }
    }
    return this;
}
EventGroup.prototype.listen = function(type, func) {
    var target = this.target;
    var handlers = this.handlers[type];
    if (handlers) {
        for (var i = 0; i < handlers.length; i++) if (handlers[i] === func) break;
        if (i == handlers.length) handlers.push(func);
    } else {
        this.handlers[type] = [func];
        if (target.addEventListener) {
            target.addEventListener(type, this.delegate, false);
        } else if (target.attachEvent) {
            target.attachEvent('on' + type, this.delegate);
        } else {
            target['on' + type] = this.delegate;
        }
    }
    return this;
};
EventGroup.prototype.unlisten = function(type, func) {
    var target = this.target;
    var handlers = this.handlers[type];
    if (handlers && func) {
        for (var i = 0; i < handlers.length; i++) {
            if (handlers[i] === func) {
                handlers.splice(i, 1);
                break;
            }
        }
        if (handlers.length) return this;
    }
    handlers = null;
    if (target.removeEventListener) {
        target.removeEventListener(type, this.delegate, false);
    } else if (target.detachEvent) {
        target.detachEvent('on' + type, this.delegate);
    } else {
        target['on' + type] = null;
    }
    return this;
};
EventGroup.prototype.destroy = function(type) {
    for (var type in this.handlers) if (this.handlers.hasOwnProperty(type)) {
        this.unlisten(type);
    }
};