Question

I am working through “JavaScript Web Applications” an want to append the class library I created. Here is the fiddle http://jsfiddle.net/andrewjmead/gXMp8/. Right now it works, but I remember hearing it is best to avoid using __proto__ in your code. I am currently using this to create functions to manipulate private variables.

Right now the Cat class inherits from the Animal class. I want to add a private variable “name” in the constructor for cat and then create a getName and setName to manipulate this value for each instance.

Var tom = Cat("tom");
tom.setName("fud");
tom.getName(); //fud

Should I be using this.getName() instead of this.proto.getName(), or am I wrong altogether?

Answer 1

I think in dynamic languages like javscript, or Python, there are no needs for really private variables. When we say something private, we actually say “Don’t touch this stuff if you don’t know what you are doing”. So don’t be too strict about the private thing. And, if you really want to keep some variables private, I prefer using closure. it is a good approach to make some variable really private. For example:

function Cat(name){
    var _name = name;

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

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

In this approach, there is no way to access the _name variable out of Cat. But there are drawbacks you can easily figure out, that you have to write your getter and setter methods inside of constructor function. The fancy Cat.prototype.someFunc declaration gone.

In my real work, I used to work with javascript for 2 years, I am favor of using the leading _ to tell others, this is a private variable, cause I am a Python fan. 😉