Question: Simple as that, can we emulate the "protected" visibility in Javascript somehow?

Answer: 
[Sure](http://webreflection.blogspot.com/2008/02/how-to-inject-protected-methods-in.html) you can. Here's another [example](http://blog.blanquera.com/2009/03/javascript-protected-methods-and.html).
There's an interesting pattern worth mentioning here: a JavaScript contructor function may return any object (not necesserily *this*). One could create a constructor function, that returns a proxy object, that contains proxy methods to the "real" methods of the "real" instance object. This may sound complicated, but it is not; here is a code snippet:

```
var MyClass = function() {
    var instanceObj = this;
    var proxyObj = {
        myPublicMethod: function() {
            return instanceObj.myPublicMethod.apply(instanceObj, arguments);
        }
    }
    return proxyObj;
};
MyClass.prototype = {
    _myPrivateMethod: function() {
        ...
    },
    myPublicMethod: function() {
        ...
    }
};

```

The nice thing is that the proxy creation can be automated, if we define a convention for naming the protected methods. I created a little library that does exactly this: <http://idya.github.com/oolib/>