[oop] Call an overridden method from super class in typescript

below is an generic example

    //base class
    class A {
        
        // The virtual method
        protected virtualStuff1?():void;
    
        public Stuff2(){
            //Calling overridden child method by parent if implemented
            this.virtualStuff1 && this.virtualStuff1();
            alert("Baseclass Stuff2");
        }
    }
    
    //class B implementing virtual method
    class B extends A{
        
        // overriding virtual method
        public virtualStuff1()
        {
            alert("Class B virtualStuff1");
        }
    }
    
    //Class C not implementing virtual method
    class C extends A{
     
    }
    
    var b1 = new B();
    var c1= new C();
    b1.Stuff2();
    b1.virtualStuff1();
    c1.Stuff2();