alt Hacker NewsI don't understand the point about comments. Why shouldn't they be allowed? What object model?
>Comments shouldn't have been allowed basically everywhere in CSS (compare to HTML, which basically only allows them where content goes), because it makes them basically unrepresentable in the object model, which in turn makes building editing directly on top of the object model impossible
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I'm guessing they mean that comments shouldn't be allowed everywhere, not that they shouldn't be allowed at all? i.e. CSS lets you put comments in many more places than HTML, in such a way that it's hard to practically impossible to represent in an AST? At least that's how I read it
The CSS Object Model.
HTML comments are basically just a HTML tag that isn't rendered. Tools that 'compile' the HTML code into a document tree, including browsers, preserve comments as nodes without any extra effort.
CSS comments can go anywhere:
/*wow*/ .selector /*x*/ {animation /*z*/: 2s /*z*/ linear /*z*/ bounce;}
Same reason why JSON prohibits comments: When you parse it, there is no place to represent the comments in the JavaScript object and array tree, so they must be thrown away, therefore it's impossible to write it out with the same comments in the same places.
Same thing with white space: JSON can not round trip white space or comments the way XML or HTML can, because XML and HTML DOM represents comments and white space explicitly.
Also you can't put comments inside elements like <div <--! comment --> class="foo">. There is no way to represent a comment inside an element in XML or HTML DOM.
But CSS lets you, so you can't round trip comments in CSS.
Imagine you have something like `width /comment/: /comment2 /12px /comment3/,`. Now you want to load your css into some kind of structured representation, rearrange it, then spit it back out again with that comment intact. The requirement to represent such comments in your structured format so you can retain them is really obnoxious. In html you can just view comments as another node in a uniform tree.