Description

Constructable Stylesheets and adoptedStyleSheets enable adding styles directly to DOM trees, e.g. document and shadow roots, without creating new DOM elements. Because a single stylesheet object can be adopted by multiple scopes, it also allows sharing of styles that can be centrally modified.

General consensus; shipped in both Chrome and Firefox, not available in Safari

Rationale

• There is no effective way to share styles across components while allowing them to be centrally modified.
• Creating <style> elements for each style used in each shadow root has a measurable performance overhead.
• CSS Module Scripts, another critical feature, depends on constructible stylesheets.

Specification

https://w3c.github.io/csswg-drafts/cssom-1/

Tests

Those including "constructable" in https://github.com/web-platform-tests/wpt/tree/master/css/cssom