[whatwg] Comment Syntax and Parsing
Lachlan Hunt
lachlan.hunt at lachy.id.au
Sat Jan 21 20:57:23 PST 2006
Hi,
This is somewhat in response to Ian's recent article about comment
parsing [1].
Firstly, Ian, could you please clarify what exactly made you change your
mind about this issue, after seven years of pushing (mostly) proper SGML
comment handling and which eventually resulted in 5 implementations
(Mozilla, Safari, Opera, Konqueror and Prince)? I assume, of course,
this now means that all of those browsers will soon, if not already, be
removing such support?
Secondly, what will now be defined as a conforming comment syntax for
use in a document? Ignoring parsing requirements, is it safe to assume
that HTML will borrow from the stricter XML comment syntax, which start
with '<!--' and end with '-->' and does not contain '--' anywhere in
between?
In other words:
<!-- valid comment -->
<!-- invalid -- comment -->
<!-- invalid -- -- comment --> (though, valid in HTML4)
That seems like the most backwards compatible method, it remains
compatible with the HTML4 syntax and is actually the way most good
tutorials teach authors to write comments.
What about the empty comment declaration: <!> ? I've never seen anyone
use it (except in test cases), and I tested it with your new live DOM
viewer tool and these were the results:
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C%21DOCTYPE%20html%3E%0A%3Ctitle%3Etest%3C/title%3E%0A%3Cp%3Etest%3C%21%3Etest%3C/p%3E
Firefox 1.5.0.1: Treated as comment
IE 6: Rendered the document properly, though the DOM view
showed nothing but: #comment: CTYPE ht
Opera 9/Win: CRASHED!
Opera 9/Mac: CRASHED!
Opera 8.5/Mac: Ignored (not shown in DOM view)
Safari 2.0.3: Ignored (not shown in DOM view)
As a result, and because nothing is gained by using it, it too should be
considered non-conformant, but should be parsed as a comment, like
Firefox does.
[1] http://ln.hixie.ch/?start=1137799947&count=1
--
Lachlan Hunt
http://lachy.id.au/
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