CODEWITHSUNDEEP
javascriptobject
Ivan
Ivan

Reputation: 40778

Saving an object inside itself

How come I can store an object as it's own property? Here is a simple example:

let obj = {};
obj['obj'] = obj;

This will result in having an infinite object tree: I can call obj with obj.obj.obj.obj or even with obj.obj.obj.vobj.obj.obj.obj.obj.

Is this an issue for performance? It doesn't seem to bother the browser at all.

Actually, when I look at the console in Chrome and click to expand obj's properties it says (on the tooltip of i):

Value below was evaluated just now

So they were evaluated just when I clicked to expand.

enter image description here

Does this mean that JavaScript too will not look at obj's property until I actually access them?

Is obj.obj just a reference to obj?

Upvotes: 2

Views: 407

Answers (1)

Jonas Wilms
Jonas Wilms

Reputation: 138557

Is this an issue for performance?

No. A circular reference is just as every other reference. Every class instance has actually a circular reference:

instance.constructor.prototype.constructor.protototype

Is obj.obj just a reference to obj?

Yes.

Does this mean that JavaScript too will not look at obj's property until I actually access them?

Yes. And the console won't try to expand it as it would get caught up in an endless loop.

Upvotes: 2

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