MooTools when method

gistfile1.js

Function.implement({
	'when': function(check, interval, bind)
	{
		var bind = bind || this,
			timer = setInterval(function() {
				if (check.apply(bind))
				{
					clearInterval(timer);
					this.apply(bind);
				}
			}.bind(bind), (interval || 100));
	}
});