SO#20630605

/*
function BaseFunc(x, y) {
    this.X = x;
    this.Y = y;
}
*/
class Base {
    public X;
    public Y;
    function Base(x,y) {
        this.X=x;
        this.Y=y;
    }
}

/*
function DerivedFunc(x, y, z) {
    this.Z = z;
    BaseFunc.call(this, x, y);
}

DerivedFunc.prototype = new BaseFunc;

DerivedFunc.prototype.sayHello = function () {
    alert("Result is: " + (this.X + this.Y + this.Z));
}
*/
class Derived : public Base {
    public Z;
    function Derived(x,y,z)::Base(x,y) {
        this.Z=z;
    }
    function sayHello() {
        /* alert */
    }
}

/*
function Test() {
    var d = DerivedFunc(1, 2, 3);
    var b = new BaseFunc(4, 5);
    d.sayHello();
    b.sayHello();
}
*/
var d = new Derived(1,2,3);
var b = new Base(4,5);
d.sayHello();// OK
b.sayHello();//Error