CSS WG Blog Updated Working Draft of Selectors Level 4

Updated Working Draft of Selectors Level 4

The CSS Working Group has published an updated Working Draft of Selectors Level 4. Selectors are patterns that match against elements in a tree and are used as a core part of CSS and in DOM methods such as .querySelector(). This update adds, drops, and renames a number of selectors:

• zero-specificity pseudo-class named :where()
• :matches() renamed to :is()
• :blank defined to select empty user input elements
• :empty tentatively redefined to ignore whitespace-only text nodes
• :drop() dropped due to removal of support in HTML
• Added case-sensitive attribute value matching flag s.

In addition, the specificity rules for :is() and :nth-child() were altered to use the most specific selector argument rather than the most specific selector that happened to match. See specificity rules in the spec and
and discussion leading up to this change in Issue 1027.

Changes since the February 2018 WD are all listed in the Changes section.

One major issue that’s open is redefining the way invalid selectors are handled within :is() and similar pseudo-classes to ignore unknown selectors rather than invalidating the entire style rule. See Issue 3264. Another series of open issues concerns the :visited pseudo-class and how to balance security concerns with usability requirements. Other remaining work is largely clarifications and better integration with the DOM and HTML specifications.

Please send feedback by either filing an issue in GitHub (preferable) or sending mail to the (archived) public mailing list www-style@w3.org with the spec code ([selectors-4]) and your comment topic in the subject line. (Alternatively, you can email one of the editors and ask them to forward your comment.)

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