JavaScript Tutorial/Object Oriented/instanceof

Using instanceof operator to check the subclass created by Prototype Chaining

function SubClass() {
}
SubClass.prototype = new BaseClass();
SubClass.prototype.name = "";
SubClass.prototype.sayName = function () {
    alert(this.name);
};
var objA = new BaseClass();
var objB = new SubClass();
var objB = new SubClass();
alert(objB instanceof BaseClass);    //outputs "true";
alert(objB instanceof SubClass);    //outputs "true"