[whatwg] Empty elements
Jukka K. Korpela
jkorpela at cs.tut.fi
Sat Aug 27 21:26:26 PDT 2011
28.8.2011 3:10, Nils Dagsson Moskopp wrote:
> Bronislav Klučka <Bronislav.Klucka at bauglir.com> schrieb am Sun, 28 Aug
> 2011 01:56:15 +0200:
>> HTML5 defines several void elements.
>> I think this enumeration is insufficient, and I'd like to suggest to
>> simply allow every element to have syntax with /> at the end if such
>> element has no content.
> This would most certainly not be backwards-compatible.
Indeed. The validator validator.nu (and its close in the W3C Markup
Validator) reflects common browser behavior when it reacts to e.g. <p/>
Error: Self-closing syntax (/>) used on a non-void HTML element.
Ignoring the slash and treating as a start tag.
So allowing e.g. <script src=foo /> would mean that existing browsers
would treat subsequent data, up to the end of data or the first
occurrence of </script>, whichever occurs first, as a script.
The word "void", though used even in the validator's message, is at
least misleading if not incorrect. The correct word is "empty".
The interesting question is: Where do the normative rules say that
self-closing syntax must not be used for other than empty elements?
The XHTML serialization rules say, at
"The syntax for using HTML with XML, whether in XHTML documents or
embedded in other XML documents, is defined in the XML and Namespaces in
XML specifications. [XML] [XMLNS]
This specification does not define any syntax-level requirements beyond
those defined for XML proper.
The XML spec says, at
"For interoperability, the empty-element tag SHOULD be used, and SHOULD
only be used, for elements which are declared EMPTY."
So it is just a SHOULD, not MUST. Besides, there is no concept of being
declared EMPTY in HTML5, as no DTD is provided.
> Have you tried using the XML serialization instead?
How would things be different in XML serialization? The whole idea of
"self-closing" tags is an XML idea, and it would be rather pointless to
use them in HTML serialization at all - there it is much more natural to
write <br> and not <br/> or <br />.
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