[whatwg] self-closing tags in html5
William F Hammond
hammond at csc.albany.edu
Fri Dec 31 10:59:33 PST 2010
Ian Hickson <ian at hixie.ch> writes:
> On Sat, 25 Sep 2010, William F Hammond wrote:
>> In the spec at 220.127.116.11 (6) (for the text/html serialization):
The section number refers to the W3C version at
>> Then, if the element is one of the void elements, or if the
>> element is a foreign element, then there may be a single U+002F
>> SOLIDUS character (/). This character has no effect on void
>> elements, but on foreign elements it marks the start tag as
>> It would be better to allow self-closing tags on all de facto empty
>> elements, foreign or not and defined-empty or not.
> you further clarify "de facto empty" as meaning:
> | A defacto empty element is an element that is either defined-empty in
> | the document type definition OR any element in the current document
> | instance that has no content.
> While syntactic sugar to make "<foo/>" equivalent to "<foo></foo>" even
> for elements that are not void elements would probably be quite popular,
> it is unfortunately incompatible with legacy content. It turns out that
> there is a large amount of content that includes "/" characters in
> positions that appear to be the end of the start tag but that do not
> intend to have the browser close the element immediately.
> For example, markup such as the following is sadly common:
> <p/>Hello world!</p>
My comment about cognitive dissonance in
is also relevant here.
The parsing rules of section 8.2 (W3C version) in the html5 spec do
adequately separate the cases.
So as I read those rules (on September 25):
1. your example above would be parsed as a non-empty paragraph
2. <a href=http://example.foo/>an example</a>
would be parsed with the '/' as part of the url
3. <a id="mylabel"/> OR <a id=mylabel />
would be understood as self-closing under section 8.2 but then
handled as regular open tags. That is cognitive dissonance. Then
because <a> has transparent content, the nonsense can be propogated
through several paragraphs.
Why not re-write 18.104.22.168 (6) as follows:
Then there may be a single U+002F SOLIDUS character (/). This
character has no effect on void elements. On foreign elements it
marks the start tag as self-closing. On non-void HTML elements it
marks the start tag as self closing if it is immediately preceded by
whitespace or by a single instance of one of the two markup quoting
characters U+0022 or U+0027; otherwise it has no effect, and the
start tag is not understood as self-closing.
Without language of this type the specification has not actually
covered the example you cited, i.e.,
<p/>Hello world!</p> ,
where the <p/> should not be self-closing
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