Javascript prototype and object examination

InitialePrototype Examination

//Here we define Person object by creating a constructor for it. We could also do this by doing new Object() then dynamically
//adding attributes and functions to it.
var Person = function(name, age){
    this.name = name;
    this.age = age;
    this.getAge = function(){
        return this.age;
    };
    this.toString = function(){return "Person";};
};

//Creates John as a object of type Person. John has no prototype because he has no constructor function. He is simply an
//object of type Person. If one changes/modifies Person's prototype the changes will be propogated to John.
var John = new Person("John");

//Create customer object type and set its prototype to Person with same name and age. This means that any changes to Person
//object type should propogate to Customer.
var Customer = function(name, age){
    this.name = name;
    this.age = age;
    this.getAge = function(){return age;};
};

//Set Customer Prototype.
Customer.prototype = new Person();

//Create Ellen as an object of type Customer.
var Ellen = new Customer("Ellen","21");




alert('John prototype: '+John.prototype.toString()));
alert('Ellen prototype: '+Ellen.prototype.toString());