[csswg-drafts] [selectors-4] :nth-child and friends are either underdefined or defined wrong

SimonSapin has just created a new issue for https://github.com/w3c/csswg-drafts:

== [selectors-4] :nth-child and friends are either underdefined or defined wrong ==
All of these

* https://drafts.csswg.org/selectors/#the-nth-of-type-pseudo
* https://drafts.csswg.org/selectors/#the-nth-last-child-pseudo
* https://drafts.csswg.org/selectors/#the-nth-of-type-pseudo
* https://drafts.csswg.org/selectors/#the-nth-last-of-type-pseudo

have a definition that includes “the An+Bth element” with no details on what that means. This is either wrong (since this is using “the element” singular, where as multiple elements could match) or at least under-defined. A and B are from https://drafts.csswg.org/css-syntax/#anb, but what is n?

This is a regression from Selectors Level 3, which has a precise definition:

https://drafts.csswg.org/selectors-3/#nth-child-pseudo
> The :nth-child(an+b) pseudo-class notation represents an element that has an+b-1 siblings before it in the document tree, for any positive integer or zero value of n, and has a parent element.  

Notable edge cases that should be well-defined include n<0 and A=0.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/1292 using your GitHub account

Received on Tuesday, 25 April 2017 10:46:44 UTC