1. :focus-within CSS pseudo-class

    The `:focus-within` pseudo-class matches elements that either themselves match `:focus` or that have descendants which match `:focus`.

  2. Media Source Extensions

    API allowing media data to be accessed from HTML `video` and `audio` elements.

  3. dommatrixreadonly api: `scalenonuniformself()`

  4. javascript built-in: webassembly: module: customsections