best approach to member variables in object-oriented javascript?

Question

This is a follow up to a question I just posted. I'm wondering how you all handle member variables in javascript clases when using MyClass.prototype to define methods.

If you define all of the methods in the constructor function:

function MyClass(){
 this.myMethod = function(){}
}

You can very nicely declare member variables and access them from inside your methods:

function MyClass(){
 var myVar = "hello";
 this.myMethod = function(){
  alert(myVar);
 }
}

When using the Object.prototype technique, you lose this nicety, and have to do it like this;

function MyClass(){}
MyClass.prototype.myVar = "hello";
MyClass.prototype.myMethod = function(){alert(this.hello)};

I'm not crazy about having to write "this" every time I access a member variable. I want to use the Object.prototype approach for memory and flexibility reasons, but it seems a lot clumsier syntax-wise. Is this how you folks generally work?

thanks,

-Morgan

Answer 1

You should get over your aversion to using the this pointer to access member variables.

Assign member variables in the constructor, and you can access them with prototype methods:

function Cat(){
    this.legs = 4;
    this.temperament = 'Apathetic';
    this.sound = 'Meow';
}

Cat.prototype.speak = function(){alert(this.sound)}

var cat = new Cat();
cat.speak();

Yes those object attributes are public but, as Guido would say, we're all adults here. Javascript is, after all, a plain-text, loosely-typed, interpreted language. The benefits of "private" variables in this environment are shaky at best.

I say just be explicit and obvious about how your object should be accessed, and violators will stray from that at their own risk.