Using instanceof operator to check the subclass created by Prototype Chaining : instanceof « Object Oriented « JavaScript Tutorial

1. JavaScript Tutorial
2. Object Oriented
3. instanceof

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"