javascript oop, instanceof and base class
===

I am desinging some class hierarchy in javascript. It works fine so far, but I can't see how to determine if an object is an "instance" of a parent class. Exemple:

    function BaseObject(name){
    	this.name = name;
    	
    	this.sayWhoAmI = function(){
    		console.log(this.name + ' is a Derivation1 : ' + (this instanceof Derivation1));
    		console.log(this.name + ' is a Derivation2 : ' + (this instanceof Derivation2));
    		console.log(this.name + ' is a BaseObject : ' + (this instanceof BaseObject));
    	};
    }
    function Derivation1(){
    	BaseObject.apply(this, ['first derivation']);
    }
    function Derivation2(){
    	BaseObject.apply(this, ['second derivation']);
    }
    
    var first = new Derivation1();
    var second = new Derivation2();



`first.sayWhoAmI();` logs this:

    first derivation is a Derivation1 : true
    first derivation is a Derivation2 : false
    first derivation is a BaseObject : false


while `second.sayWhoAmI();` logs this :

    second derivation is a Derivation1 : false
    second derivation is a Derivation2 : true
    second derivation is a BaseObject : false


I feel like both `first` and `second` object should have say that they are instances of BaseObject.

I understand that javascript may not be made for this, but I wonder if there's a way to achieve that.