How to refer to the first object called?

Question

I have this code:

var Person = {
 "name": "",
 "changes": {
  "name to": function(value) {
   this["name"] = value;
  }
 }
}

var Josh = Object.create(Person);
Josh["changes"]["name to"]("John");

console.log(Josh.name); // nothing
console.log(Josh.changes.name); // "John"

The problem is that this above refers to Object "changes" and not object instance "Josh".

I can't replace this with Person because then it's referring to the object "Person" and not to the object instance "Josh".

Is it possible to refer to Josh's name?

What is the "changes" object for? It doesn't appear to serve any purpose. It'd be more natural to have a `Person.changeName()` function. — John Kugelman, Nov 28 '10 at 08:33
This was just a simplification of the actual implementation. The principle is the same though. — ajsie, Nov 28 '10 at 08:34
From an OO pov, it seems a bit strange. An object is supposed to encapsulate data and methods to operate on that data. You're isolating your methods to another object. — Martin Algesten, Nov 28 '10 at 08:47

score 2 · Accepted Answer · answered Nov 28 '10 at 08:57

Why don't you use the more common form of Javascript OOP?

function Person() {
    this.name = "";
    this.changes = {};
    var _this = this;
    this.changes.nameTo = function(name) {
        _this.name = name;
    }
}

var Josh = new Person();
Josh.changes.nameTo("John");

console.log(Josh.name); // "John"
console.log(Josh.changes.name); // undefined

Martin Algesten · Answer 2 · 2010-11-28T09:01:02.717

0

Sadly not. You don't have any reference to an enclosing instance of the object you're in currently. You need to move the method to the outer Person object.

var Person = {
 "name": "",
 "changeNameTo": function(value) {
   this["name"] = value;
 }
}

Edit: If you absolutely want the original structure, albeit strange from an OO perspective. You need to give the inner object a reference to the outer. Programatically you can do it as below - or perhaps do it in a constructor, depending on your framework providing the Object.create() method.

var Person = {
 "name": "",
 "changes": {
  "name to": function(value) {
   this.data["name"] = value;
  }
 }
}

var Josh = Object.create(Person);
Josh.changes.data = Josh;

Josh["changes"]["name to"]("John");

edited Nov 28 '10 at 09:01

answered Nov 28 '10 at 08:33

Martin Algesten

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Isn't it possible to use caller/callee to get the first object called: Josh["changes"]["name to"]("John") which in this case is Josh? – ajsie Nov 28 '10 at 08:38
Ha! Yeah, I suppose - but that's so obscure, I'd completely forgotten about it. Seems it's deprecated even http://stackoverflow.com/questions/103598/why-was-the-arguments-callee-caller-property-deprecated-in-javascript – Martin Algesten Nov 28 '10 at 08:41
Do you know how I could use caller/callee in my case to get Object Josh? – ajsie Nov 28 '10 at 08:47
Hm.. on second thoughts, I was confused. `Josh["changes"]["name to"]("John");` The `arguments.callee` is the inner function, but `arguments.callee.caller` is (of course) not the outer. – Martin Algesten Nov 28 '10 at 08:56

How to refer to the first object called?

2 Answers2