how to declare abstract classes within object declaration javascript

example.js

// the way it's done in the question (http://stackoverflow.com/questions/16963111/javascript-class-inheritance-for-functions/16963189#16963189)
MyBase = function() {
    this.m_Stuff = 0; // etc
};
MyBase.prototype.MySuperFunction = function (arg1) {
    alert("Hello" + arg1);
};

// how i would like to do it
MyBase = function() {
    this.m_Stuff = 0; // etc
    // define functions that can be overridden by subclasses  
    MyBase.prototype.MySuperFunction = function (arg1) {
        alert("Hello" + arg1);
    };
};