event.js

(function(exports) {

	var idCounter = 0,
		PREFIX = '_',
		PREFIX_REG_EXP = new RegExp('^' + PREFIX + '+');

	var uniqueId = function(prefix) {
		var id = ++idCounter + '';
		return prefix ? prefix + id : id;
	};

	var Event = {
		on: function(events, callback, context) {
			var src, uid, evt, tail, name;

			this._events = this._events || {};
			events = events.split(/\s+/);

			while ((evt = events.shift())) {
				evt = evt.replace(/^:+|:+$/g, '').replace(/:+/g, ':');
				src = evt;
				evt = evt.split(':');
				if (typeof callback === 'function') {
					uid = uniqueId(PREFIX);
					tail = this._events;
					while (typeof(name = evt.shift()) !== 'undefined') {
						name = name.replace(PREFIX_REG_EXP, '');
						if (name) {
							tail[name] = tail[name] || {};
							tail[name][uid] = {
								_by: src,
								fn: callback,
								ctx: context || this
							};
							tail = tail[name];
						} else {
							continue;
						}
					}
				}
			}

			return this;
		},

		off: function(events, callback) {
			var evt, tail, name, src, k, last,
				offNames = {};
			if (!events) {
				this._events = {};
				return this;
			}
			this._events = this._events || {};
			events = events.split(/\s+/);
			while ((evt = events.shift())) {
				evt = evt.replace(/^:+|:+$/g, '').replace(/:+/g, ':');
				src = evt;
				evt = evt.split(':');
				tail = this._events;

				head = tail[evt.shift()];

				for (k in head) {
					if (head.hasOwnProperty(k) && k.match(PREFIX_REG_EXP)) {
						if (typeof callback === 'function') {
							if (head[k].fn === callback && head[k]._by.indexOf(src + ':') === 0) {
								offNames[k] = head[k]._by.split(':');
							}
						} else {
							if (head[k]._by.indexOf(src) === 0) {
								offNames[k] = head[k]._by.split(':');
							}
						}
					}
				}

				for (k in offNames) {
					if (offNames.hasOwnProperty(k)) {
						tail = this._events;
						last = offNames[k].pop();
						while ((name = offNames[k].shift())) {
							if (tail[name]) {
								delete tail[name][k];
							}
							tail = tail[name];
						}
						if (tail) {
							delete tail[last];
						}
					}
				}
			}

			return this;
		},

		fire: function(events) {
			var args = [].slice.call(arguments, 1),
				contains = function(a, b) {
					return a === b || a.indexOf(b + ':') === 0;
				},
				evt, tail, name, src, by, k;

			this._events = this._events || {};
			events = events.split(/\s+/);

			while ((evt = events.shift())) {
				evt = evt.replace(/^:+|:+$/g, '').replace(/:+/g, ':');
				src = evt;
				evt = evt.split(':');
				tail = this._events;

				while (typeof(name = evt.shift()) !== 'undefined') {
					tail = (tail && tail[name]) || tail;
				}

				for (k in tail) {
					if (tail.hasOwnProperty(k) && k.match(PREFIX_REG_EXP)) {
						by = tail[k]._by;
						if (contains(by, src) || contains(src, by)) {
							tail[k].fn.apply(tail[k].ctx, args.concat({
								type: src,
								current: by
							}));
						}
					}
				}
			}
			return this;
		}
	};

	exports.Event = Event;
})(this);

// for test
var Event = this.Event;
var fn = function() {
	console.log(arguments);
};
Event.on('a:bb:ccc', fn);
Event.on('a:bb:ddd', function() {
	console.log(arguments);
});
Event.on('a:bb:eee', fn);
Event.on('a:bb:eee:ffff', function() {
	console.log(arguments);
});

Event.on('a:bb:eee:gggg', fn);

Event.on('a:xxx:yyy', fn);

Event.on('a:b:c', function() {
	console.log(arguments);
});

Event.fire('a:bb:eee:ffff');

console.log(Event._events);