How should I setup circular refs in JavaScript

Question

I have a small little problem in JavaScript. I would like to do the following:

var peter = {
  pet : spot
}

var spot = {
  owner : peter
}

The above code runs fine but peter.pet will be undefined. While spot.owner will be defined. IS there a better way then doing stuff like :

var peter = {
  pet : 'spot'
}

var spot = {
  owner : peter
}

peter.pet = eval(peter.pet)

Any insight will be appreciated...

Just one comment, because someone should say it: When I first read the question title, my immediate answer was "You shouldn't!" I'm sure you know that circular references are generally a bad programing habit. I'm not saying never use them, but in most cases they're a sign that you need to rethink the way your objects are set up. — Scott Mermelstein
– Scott Mermelstein, Commented Jul 22, 2013 at 19:11
In general I would agree with you 100%.But, there is certain instances where it is just easier to not try and flatten the structure. — Johan
– Johan, Commented Jul 22, 2013 at 19:14

Scott Mermelstein · Accepted Answer · 2013-07-22 19:15:17Z

5

Since objects are dynamic, just add pet later:

var peter = {
    // anything else you want to set
};

var spot = {
    owner : peter
};

peter.pet = spot;

EDIT - removed a bad attempt at adding a function to the peter object. To do it right, see Renan's post.

edited Jul 22, 2013 at 19:15

answered Jul 22, 2013 at 19:04

Scott Mermelstein

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2 Comments

Geeky Guy Over a year ago

You ninja'ed me, so +1 for you.

Johan Over a year ago

I like this since its essentially what I decided to do. Its explicit and I don't need to go all OOP to do something simple.

David Riccitelli · Accepted Answer · 2013-07-22 19:04:30Z

3

Set the reference after you created spot:

var peter = {
  pet : undefined
}

var spot = {
  owner : peter
}

peter.pet = spot

answered Jul 22, 2013 at 19:04

David Riccitelli

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Comments

Geeky Guy · Accepted Answer · 2013-07-22 19:04:40Z

2

var peter = {};
var spot = {owner: peter};
peter.pet = spot;

Alternatively, you could strenghen the typing:

PetOwner = function () {};
PetOwner.prototype.pet = null;

Animal = function (owner) {
    this.owner = owner;
    this.owner.pet = this;
};
Animal.prototype.owner = null;

var peter = new PetOwner();
var spot = new Animal(peter);

answered Jul 22, 2013 at 19:04

Geeky Guy

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1 Comment

Scott Mermelstein Over a year ago

But your function setup was better than mine, so +1 to you! :-)

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