Node.cloneNode () is incompatible with DOM Spec

It is well documented (mostly on SO) that using Node.cloneNode(true)

in <input type="text">

returns a new <input>

node with the same text content as the original, but clones a <select>

(after the user selected) returns a new one <select>

without the user selecting. This is not in line with the spec at first because according to DOM 3 :

cloneNode


Returns a duplicate of this node, i.e. Serves as a generic copy constructor for nodes. The duplicate node has no parent (parentNode is null) and no user data. User data associated with the imported node is not migrated.

The answer to why this is happening is explained somewhat later, but it is clearer in the DOM 2 spec .

cloneNode


Cloning the Element copies all attributes and their values, including those generated by the XML processor to represent the default attributes, but this method does not copy any text unless it is a deep clone, since the text is contained in the child Text node.

I agree to accept this behavior with this wording in mind, although I would say it <input>

does not contain text node since the property childNodes

for <input>

will always be empty NodeList

regardless of whether it contains text (in the spec spec "has text node").

At least I understand that user selectable <option>

counts as user data, so it makes sense that this is not cloned. In this case, this "user data" is contained in the property selected

<option>

.

However, when trying to execute behavior using radio buttons and checkboxes , the behavior in Chrome 38, FF 33, Safari 6.2 completely ignores the above definition. Cloning checked checkboxes or selected radio buttons maintains their checked state. This seems to contradict the specification, as this information is "user data" that (for example <select>

) is contained in the property (in this case checked

).

Is it correct that this is out of specification? If not, is there somewhere else where this behavior is defined? And if so, is there a use case explaining why it is cloneNode()

so inconsistent with how it clones the states of user input fields?

Edit. By testing this on my set of browsers, I found that Opera 12.15 works as I would like with inputs <select>

. Namely, it stores the user's selection on the clone.