TMCom: Now Real XHTML 5

As mentioned in a previous post, my site has gone to the HTML 5 doctype. I had come from XHTML 1.0 and wanted to continue with the XML syntax of HTML 5, but my site wouldn’t validate with the XML declaration. I recently remembered that I had been serving my site with the mime-type “text/html”, which is allowed in XHTML 1.0 transitional. HTML 5 got stricter, and if you want to use the XML syntax, it must be served as “application/xhtml+xml” or “application/xml”.

So I modified the doctype switcher I had made (mentioned in that previous post) to change the mime-type to “application/xhtml+xml” when the configuration doctype was set to “xhtml5”. But IE evidently cannot handle that mime-type, so I set up my switcher to output as “html5” for IE, but “xhtml5” for other browsers. I reset the doctype variable (now an attribute of a page object):

if($this->doctype == 'xhtml5' && strstr($_SERVER['HTTP_USER_AGENT'], 'MSIE'))
    $this->doctype = 'html5';

I send my “Content-type” header only for a doctype of “xhtml5”:

if($this->doctype == 'xhtml5')
    header("Content-type: application/xhtml+xml;charset=utf-8");

And, since I’ve removed the now optional “xmlns” and “xml:lang” attributes for the “head” tag in HTML 5, I make sure to put them back in for XHTML 5:

if($this->doctype != 'html5' && !defined('pagIsXSLT')): echo 'xmlns="" xml:lang="en"'; endif;

Most other output is the same for HTML 5 and XHTML 5.

I have not actually verified this works in IE, since I don’t have access to it. I did verify that sending a user agent string from IE 7 does change the doctype properly though.

For my XML sitemap, I had been just sending it as XHTML 1.0 still, since XSLT doesn’t have an HTML 5 doctype for the “xsl:output” declaration. However, the comments on this post pointed to a solution: the doctype legacy string format. My “xsl:output” element now looks like this:

<xsl:output method="html" indent="yes" doctype-system="about:legacy-compat" />

It renders just fine in both iCab (WebKit) and Firefox. I, of course, haven’t tested this in IE.

[Update 2010-8-15] Updated the xsl:output declaration to reflect the changes to the recommendation as pointed out by Andreas Riedmüller. Had been:

<xsl:output method="html" indent="yes" doctype-public="XSLT-compat" />