Comment by matt_kantor

3 days ago

> in HTML you have a tree of nodes but comments can be anywhere

Maybe I'm misunderstanding, but no they can't. For example the comment here is not a comment, but part of the URL:

    <a href="https://example.com<!-- comment -->">click me</a>

And HTML like this is simply broken:

    <div<!-- comment -->>content</div>

Maybe you meant "they can be anywhere that a Node can be in the DOM", but I think that's more or less what the CSS "mistake" is suggesting should be true about CSS (just replace "DOM" with "CSSOM").

6 comments

matt_kantor

IshKebab 3 days ago

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 3 days ago
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
  
  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.
  
  3 replies →