nokogiri's implementation of :first is different than jQuery's.

[bryanlarsen]

jQuery's :first pseudo-selector implementation always returns only a single match. Nokogiri's implementation makes :first a synonym for :nth-child(1), which returns all elements that are the first child of their parents, which is a decidedly different result.

Since :first isn't part of the CSS standard, neither implementation is "wrong" per se, but I believe that most people would expect Nokogiri and jQuery to return the same results.

I would rather have an error message saying that :first is not supported than have it be different from jQuery.

[tenderlove]

Interesting. I would like to follow jquery, but changing this will definitely be not backwards compatible. Maybe for 2.0? @flavorjones wdyt?

[flavorjones]

Yup, better jQuery selector support is on the roadmap for 2.0. See https://github.com/tenderlove/nokogiri/blob/master/ROADMAP.md for more details.

I'll note this issue in the roadmap.