How to reference a function from JavaScript class method

Your class structure is perfectly valid. However, if your handleChange() function uses the this keyword, expecting someVar, then that is where your problem lies.

This is what happens:

1. SWFAddress.addEventListener(SWFAddressEvent.CHANGE, this.handleChange); correctly references the handler function within the class. SWFAddress caches that function to some variable f until the event is dispatched.
2. When the event is dispatched, SWFAddress calls f. While the reference to the function is preserved, the reference to the context, or this, is not. Therefore this defaults to window.

To get around this, you simply need to use an anonymous function that captures the variables within the class scope. You can call the handler with the correct context from within this anonymous function:

function SomeClass() {
    this.initializeSWFA = function() {
        // Save a reference to the object here
        var me = this;

        // Wrap handler in anonymous function
        SWFAddress.addEventListener(SWFAddressEvent.CHANGE, function (evt) {
            me.handleChange(evt);
        });
    }

    // SWFAddress suppose to call this function
    this.handleChange= function(evt) {
    // Some code here
    }

}

##An explanation of this, as requested by the OP:##

The this keyword can be explained in different ways: take a read of firstly this article about scope, and then this article about object-oriented JavaScript.

I'd like to throw in my quick reasoning too, which you may find helpful. Remember that JavaScript doesn't have "classes" as languages such as Java do. In those languages, a "method" of a class belongs only to that class (or could be inherited). In JavaScript however, there are only objects, and object properties, which can happen to functions. These functions are free agents -- they don't belong to one object or another, just like strings or numbers. For example:

var a = {
    myMethod: function () {...}
};

var b = {};
b.myMethod = a.myMethod;

In this case, which object does myMethod belong to? There is no answer; it could be either a or b. Therefore a.myMethod is simply a reference to a function, disassociated from the "context", or parent object. Therefore this has no meaning unless it is called explicitly using a.myMethod() or b.myMethod(), and thus defaults to window when called in any other way. It is for the same reason that there is no such thing as a parent or super keyword in JavaScript.