jQuery Forum

Would you be interested in trying an implementation? It does seem like it could make things faster, although it also does change the semantics from what they are currently. (I think it improves them though, so that's not necessarily a bad thing if it doesn't break stuff.) Between jsperf.com and jsfiddle.net it should be possible to build something and try it on most browsers.

Filed a ticket here : http://bugs.jquery.com/ticket/9419

We can not simply replace "copying" with "inheriting". It is semantically too different, and it would break almost every current usage of deep cloning.

jQuery.extend is usually used to create a "snapshot" of an object (the new object would not change if the original one is afterward altered). Using "object inheritance" instead, would propagate new properties to cloned objects too.

Eventually, we could introduce a new signature to jQuery.extend:

1. jQuery.extend( true, true, objA, objB, objC );

where the second "true" would indicate that deep cloning will be performed via Object.create or a similar one.

However, there is a possible problem: currently deep extending will also extent every arrays too, and we can not create new arrays inheriting other arrays. Solutions for such cases would probably be: a) inheriting arrays to obtain objects; or b) do not extend arrays on deep extending at all (that for me is insane anyway).

EDIT: Of course, there would be also: c) continue to extend new arrays even with the second argument equal to true.

@robert.katic, reading the spec for Object.create again I see what you mean. It's hard to see how the code will get faster for most cases, although the copy would definitely be better. However, I am not interested in adding more functionality to the current $.extend, it was more the lure of speeding up the current functionality since $.extend is used so widely.

Rather than replacing "copying" with "inheriting", I'm talking about the use case where the intention is make a copy of the object, as described here by John Resig:

@strada25, unfortunately they are not the same. Object.create uses the oldObject as the prototype for the new object, that's why it can be so fast:

Just echoing what others have said with a little more clarification.  Inheriting is very different from copying.