Javascript function keeps being called although its class is null

Question

I'd be happy if you could explain to me why shout() keeps getting called, although it's supposedly "gone".

var myclass = new Class({
myid: "greatidea",
initialize: function(element) {
    var shout = function() { alert(this.myid); };
    shout.periodical(5000, this); // test debug
}

});
x = new myclass ();
alert(x);
x=null;
alert(x);

also see here http://mootools.net/shell/jhCBz/

Basically, I get the idea: the function gets its own registration, and is now independent of the object who called it. But I'd be happy to get a real explanation.
Thanks.

Answer 1

x held a reference to myclass. myclass is executing shout. When you set x to null, you are just getting rid of your reference to myclass, not the myclass object itself.

Answer 2

Functions are always independent. As long as there's a reference to a function, it continues to exist. And in this case, so does your object, since you've passed a reference to it (via this) to the periodical() function, which holds onto it for context.