Yes, anywhere in the node tree. Imagine if CSS was specified in HTML-style. We might write this selector:

  h1,
  /* don't forget h2! */
  h2 {
    color: /* I love red */ "red";
  }

Like this:

  <rule>
    <selector>
      <alternative>
         h1
      </alternative> <!-- don't forget h2 -->
      <alternative>
         h2
      </alternative>
    <selector>
    <attributes>
      <color><!-- I love red --> red</color>
    </attributes>
  </rule>

Which is pretty much exactly the same as what you'd get as a CST from parsing the CSS.

▲ matt_kantor 4 days ago | parent [-]

Problem is, the CSSOM models that more like this:

    <rule selector="h1, h2">
      <style>
        <property name="color" value="red" />
      </style>
    </rule>

Perhaps your takeaway from this is "the CSSOM is bad" (and I don't necessarily disagree), but it's what the "mistake" is talking about.

▲

IshKebab 3 days ago | parent [-]

I wouldn't say that, it's more that the CSSOM doesn't try to preserve comments, which is a perfectly reasonable thing to do. I think most uses cases for modifying CSS that care about comments (e.g. auto-formatters?) would need parsers that return the full CST anyway.

▲

matt_kantor 3 days ago | parent [-]

I see. I was under the impression that you were saying the "mistake" from the post was wrong in its premise. But I guess that's incorrect, rather you think that people shouldn't use the CSSOM for use cases when comments matter, and instead they ought to design their own parsers/representations.

Just curious: do you feel the same about HTML? Should HTML allow comments in more places? I can imagine alternate ways to represent an HTML document that could capture comments within attribute lists, etc (and the DOM could exclude them entirely).

▲

IshKebab 3 days ago | parent [-]

Nah I think HTML comments are fine. I don't think there would be a benefit to allowing comments in more places and it would make it more annoying when you actually do want to process comments.

If CSS had mandated that comments could only appear in certain places (e.g. before a rule or attribute) I think that would have been fine too, though maybe slightly confusing given the resemblance to C-style comments which are allowed almost anywhere.

	▲	matt_kantor 3 days ago \| parent [-]
		Seems like we have broadly-similar perspectives, though I do find it a bit incongruent that the DOM preserves comments while the CSSOM doesn't. It feels like they ought to be in alignment one way or the other (though I also understand the historical reasons why they aren't).