Fails to parse ::part()

[Qix-]

It appears ::part() selectors do not parse and instead emit an error:

console.log(cssWhat.parse('foo::part(bar)'));

Error: Unmatched selector: )

[fb55]

Tl;dr pseudo-elements aren't allowed to have a value between parentheses.

Pseudo-elements are currently implemented in line with the CSS Selectors Spec:

A pseudo-element is made of two colons (::) followed by the name of the pseudo-element.

This is in contrast to pseudo-classes:

A pseudo-class always consists of a "colon" (:) followed by the name of the pseudo-class and optionally by a value between parentheses.

Hope this makes sense!

[fb55]

Just learned about ::part (and ::slotted). Very odd that this shouldn't be possible based on the spec. If there is a spec that allows for this, I am happy to implement it.

[fb55]

Okay, so the grammar for pseudo-elements makes them equivalent to pseudo-classes with a colon in front of them. I will update the parser to support this.

[fb55]

Thanks for the report @Qix- — this is fixed in css-what@6.1.0.

[fb55]

I have also opened w3c/csswg-drafts#7186.

[Qix-]

Thanks for the quick turnaround! :D Subscribed to the other issue, interested to see what comes of it.