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[Bug 23389] New: The implementation symantics of the HTML hidden="hidden" attribute vs CSS display:none are not clear and in fact conflict

From: <bugzilla@jessica.w3.org>
Date: Sat, 28 Sep 2013 02:46:18 +0000
To: public-html-admin@w3.org
Message-ID: <bug-23389-2495@http.www.w3.org/Bugs/Public/>
https://www.w3.org/Bugs/Public/show_bug.cgi?id=23389

            Bug ID: 23389
           Summary: The implementation symantics of the HTML
                    hidden="hidden" attribute vs CSS display:none are not
                    clear and in fact conflict
           Product: HTML WG
           Version: unspecified
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: normal
          Priority: P2
         Component: HTML5 spec
          Assignee: dave.null@w3.org
          Reporter: scunliffe.bugzilla@gmail.com
        QA Contact: public-html-bugzilla@w3.org
                CC: mike@w3.org, public-html-admin@w3.org,
                    public-html-wg-issue-tracking@w3.org

>From the current draft:
http://www.w3.org/html/wg/drafts/html/master/single-page.html#the-hidden-attribute

"User agents should not render elements that have the hidden attribute
specified."

As stated implies that user agents would be "in error" if displaying elements
when this attribute is specified.

<side_rant>I presume there is a good accessibility reason for this new
attribute but at the moment as a developer I only see trouble. I would love to
see a clear indication as to why this addition is even needed in the first
place.</side_rant>

I've created a jsbin demo showing the confusing behavior as it is currently
implemented in browsers (Firefox & Chrome from my testing)

http://jsbin.com/IKohIXe/3/edit

In short since this new HTML attribute is currently "duplicating" the same
behavior as the CSS property developers now have 2 'methods' of changing the
physical rendering of elements yet the 2 accessors are not kept in sync and the
true state of an element's display is not maintained causing "dirty data" when
inspected.

In the test case above if an element was served up with hidden="hidden" but
later JavaScript sets the CSS style "display:block" on the element the element
becomes visible... however the hidden attribute that implies that it is not
visible remains and HTMLElement.hidden returns true.

1.) Excluding any accessibility issues (which I'm presuming was the impetus for
this feature addition in the first place) I don't see any helpful use for this
attribute.
2.) IMHO, if the display of an element is altered to show through CSS the
hidden attribute (if kept) should be removed from the DOM.
3.) If it was not the intention that the hidden attribute and the CSS display
property were to affect each other in any way... then the current browser
implementations do not match the intentions.
4.) As a developer it is already confusing enough with both the CSS display and
visibility properties (especially when display can be
"block|inline|{empty_string}|table-row|inline-block" etc.) adding yet another
layer of the element is: "maybe, kinda, sorta-ish" hidden doesn't seem helpful
at all to me.

Due to the inconsistencies I've already deemed use of this attribute verboten
within my developer teams on Web Projects and from conversations with other
developers the feeling is mutual.

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Received on Saturday, 28 September 2013 02:46:20 UTC

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