Dumb Resilient Pub/Sub

pubsub.js

var sub = function (e, callback) {
	var handler;
	if (document.addEventListener) {
		handler = function (evt) {
			callback();
		};
		document.addEventListener(e, handler, false);
	} else if (document.attachEvent) {
		handler = function (evt) {
			if (evt.propertyName == e) {
				callback();
			}
		};
		document.documentElement.attachEvent('onpropertychange', handler);
	}
	return [e, handler];
};

var unsub = function (args) {
	var e = args[0],
		handler = args[1];
	if (document.addEventListener) {
		document.removeEventListener(e, handler, false);
	} else if (document.attachEvent) {
		document.documentElement.detachEvent('onpropertychange', handler);
	}
};

var pub = function (e) {
	if (document.addEventListener) {
		fauxEvent = document.createEvent('UIEvents');
		fauxEvent.initEvent(e, false, false);
		document.dispatchEvent(fauxEvent);
	} else if (document.attachEvent) {
		if (!document.documentElement[e]) {
			document.documentElement[e] = 0;
		} else {
			document.documentElement[e]++;
		}
	}
};

run.js

sub('test', function () {
	console.log('first sub');
	DOES_NOT_EXIST++; // this will throw an error
});

var yankMe = sub('test', function () {
	console.log('second sub');
});

console.log('First pass: should return 2 subs');
pub('test');

unsub(yankMe);

console.log('Second pass: should return 1 sub');
pub('test');