Question

I am trying to implement a way to achieve inheritance in JavaScript. First I define the base class, as follows:

function Person(name){
    name = name + "!"; //I want to reuse this code for initialization

    this.getName = function(){
        return name;
    };

    this.setName = function(_name){
        name = _name;
    };
};

Then I define the sub class. Happens that I need a way to call the base class constructor. Ideally I would call it from within VipPerson constructor, when I still have a reference for name param. But if I do it from that point it simply does not work and if I try to access getName from base class I get an error that VipPerson has no getName method.

function VipPerson(name, vipLevel){
    this.getVipLevel = function(){
        return vipLevel;
    };

    //the line below would not work!
    //VipPerson.prototype = new Person(name);
};

VipPerson.prototype = new Person(); //but this would. not ideal IMO

The drawback for me to set the prototype from outside the VipPerson is that I lose any reference to the parameter were passed.

Is there an elegant way to solve this? I would like to have this clean interface:

var foo = new Person("Foo");
console.log(foo.getName());

var bar = new VipPerson("Bar", 100);
console.log(bar.getName()); //error
console.log(bar.getVipLevel());

Answer 1

Have you tried this approach?

function VipPerson(name, vipLevel){
    this.__proto__ = new Person(name);

    this.getVipLevel = function(){
        return vipLevel;
    };
};