[chrismorgan]

I first touched XSLT in 2010. I appreciated what it could do, but it was painful to work with due to poor documentation and tooling. This has only gotten worse by comparison with alternatives.

You can still do XSLT in the browser. You can serve arbitrary XML and transform it. As an example, Atom feeds on my website (such as <https://chrismorgan.info/blog/tags/meta/feed.xml>) render just fine in all mainstream browsers, thanks to this processing instruction at the start of the file:

  <?xml-stylesheet type="text/xsl" href="/atom.xsl"?>

But working with it is not particularly fun, because XML support in browsers has been only minimally maintained for the last twenty or so years. Error handling is atrocious (e.g. largely not giving you any stack trace or equivalent, or emitting errors only to stdout), documentation is lousy, some features you’d have expected from what the specs say are simply unsupported (and not consistently across engines), and there are behavioural bugs all over the place, e.g. in Firefox loading any of my feeds that also fetch resources from other origins will occasionally just hang, and you’ll have to reload the page to get it to render; and if you reload the page, you’ll have to close and reopen the dev tools for them to continue working.

[bambax]

I think out of the box, browsers can only do xslt 1; but Saxon offers a JS version of their engine that does xslt 3.0 and is free (as in beer): https://www.saxonica.com/saxon-js/index.xml

[chrismorgan]

It’s actually worse than XSLT 1.0 due to inconsistencies and incompletenesses. For example, Firefox doesn’t respect <xsl:output method="html">, but uses an XML parser on the transformed result regardless; and doesn’t support disable-output-escaping. I wanted these for my Atom stylesheet (for <content type="html"> and the likes; instead I had to emit serialised HTML and decode it in JavaScript, though with difficulty I could have done feature-detection to skip that step if disable-output-escaping worked).

Even perfunctory probing shows fairly serious problems in Firefox (where Chromium is consistently much better, in this specific area). I could file quite a few bugs in short order (e.g. these mentioned, bad document.contentType values, <template> not working properly), but I don’t think there’s any interest in fixing things.

(I wrote this comment as much for my own future reference as anything else. XML/HTML polyglot stuff makes things decidedly messy at times.)