.clone(true) does not clone data properly

[kennykwok@…]

Problem found in jQuery 1.4.4.

Modification of data in cloned object will affect the original object.

Here is the sample code:

<script>
$(function() {
  var original_button = $("<input/>", {"type":"button","value":"Original"})
  .appendTo("body")
  .data("obj", ["1"])
  .bind("click", function() {
    alert($(this).data("obj").join(" - ")); });

  var clone_button = original_button.clone(true)
  .val("Clone").appendTo("body");

  clone_button.data("obj").push("2", "3", "4");
});
</script>

Result: Click on "Original" will show "1 - 2 - 3 - 4"

Expected Result: Click on "Original" should show "1"

Note: jQuery 1.4.2 does not have this issue.

[anonymous]

​http://jsfiddle.net/uvpPw/

[jitter]

​reduced test case
​test case with object instead of array

[dmethvin]

Fix: ​https://github.com/jquery/jquery/pull/126

[dmethvin]

For performance and reliability reasons (e.g., potential circular references in the data) we have decided to only copy the first level of the data object. That is also consistent with the behavior of $().data(obj) which shallow-extends the element's existing data object with obj.

Any sub-objects or arrays in the data will continue to be shared by the cloned elements. If that is not desirable, you can do something like this after the clone operation to (shallow) copy the array of strings:

clone_button.data("arr", original_button.data("arr").concat());

or to deep-copy the array,

clone_button.data("obj", $.extend(true, [], original_button.data("obj")));

or to deep-copy a sub-object in the original data,

clone_button.data("obj", $.extend(true, {}, original_button.data("obj")));

Here's an updated test case: ​http://jsfiddle.net/dmethvin/uvpPw/1/

[Colin Snover]

Fix #7717 and #7165. Thanks to dmethvin and iliakan for their help fixing these issues.

Changeset: faefbb1ad0b81e8001b582d06d5bd9c9236e62ce

[snover]

That fix was not applied.

[anonymous]

Petition: Is it possible to extend the clone() to support deep copying of data, in future version of jQuery?

e.g. clone(true, true) with the 2nd "true" to indicate deep copying of data.

[john]

There wasn't a 1.4.5 release, was actually 1.5.

[john]

There was no 1.4.5 release, was actually 1.5.

[timmywil]

This should probably be set to fixed and take out the needsdocs. The jQuery.extend has been added since snover's pull. See manipulation.js#L363.

[jitter]

Replying to timmywil:

This should probably be set to fixed and take out the needsdocs. The jQuery.extend has been added since snover's pull. See manipulation.js#L363.

I don't see this fixed. We still only copy the first level of data (extend without deep option) so ​daves comment is still the way to go for stuff like this.

So it still needs to be documented that clone(true) only copies the first level of data and thus the clone and original might share some nested data objects.

[timmywil]

Ah right, without the deep option. My bad.

[timmywil]

Ok, I've created a clap here: ​http://oksoclap.com/jQuery-clone Also, you do not need to deep extend as you are creating a new object simply by doing the extend.

Notice I've updated Dave's fiddle to not do the $.extend(true, ...) and data is still not shared. ​http://jsfiddle.net/timmywil/uvpPw/2/

[anonymous]

needsdocs may be removed. See the updated ​docs

[timmywil]

Sorry, wasn't logged in, that last comment was me.