jschrab jschrab - 1 month ago 6
Javascript Question

What is the most efficient way to deep clone an object in JavaScript?

What is the most efficient way to clone a JavaScript object? I've seen

obj = eval(uneval(o));
being used, but that's non-standard and only supported by Firefox. I've done things like
obj = JSON.parse(JSON.stringify(o));
but question the efficiency. I've also seen recursive copying functions with various flaws.

I'm surprised no canonical solution exists.


Note: This is a reply to another answer, not a proper response to this question. If you wish to have fast object cloning please follow Corban's advice in their answer to this question.

I want to note that the .clone() method in jQuery only clones DOM elements. In order to clone JavaScript objects, you would do:

// Shallow copy
var newObject = jQuery.extend({}, oldObject);

// Deep copy
var newObject = jQuery.extend(true, {}, oldObject);

More information can be found in the jQuery documentation.

I also want to note that the deep copy is actually much smarter than what is shown above – it's able to avoid many traps (trying to deep extend a DOM element, for example). It's used frequently in jQuery core and in plugins to great effect.