1. CSS :any-link selector

    The `:any-link` CSS pseudo-class matches all elements that match `:link` or `:visited`

  2. Case-insensitive CSS attribute selectors

    Including an `i` before the `]` in a CSS attribute selector causes the attribute value to be matched in an ASCII-case-insensitive manner. For example, `[b="xyz" i]` would match both `<a b="xyz">` and `<a b="XYZ">`.

  3. ::first-letter CSS pseudo-element selector

    CSS pseudo-element that allows styling only the first "letter" of text within an element. Useful for implementing initial caps or drop caps styling.

  4. selector list argument of :not()

    Selectors Level 3 only allowed `:not()` pseudo-class to accept a single simple selector, which the element must not match any of. Thus, `:not(a, .b, [c])` or `:not(a.b[c])` did not work. Selectors Level 4 allows `:not()` to accept a list of selectors. Thus, `:not(a):not(.b):not([c])` can instead be written as `:not(a, .b, [c])` and `:not(a.b[c])` works as intended.

  5. selector list argument of :nth-child and :nth-last-child CSS pseudo-classes

    The newest versions of `:nth-child()` and `:nth-last-child()` accept an optional `of S` clause which filters the children to only those which match the selector list `S`. For example, `:nth-child(1 of .foo)` selects the first child among the children that have the `foo` class (ignoring any non-`foo` children which precede that child). Similar to `:nth-of-type`, but for arbitrary selectors instead of only type selectors.

  6. CSS :read-only and :read-write selectors

    :read-only and :read-write pseudo-classes to match elements which are considered user-alterable

  7. CSS 2.1 selectors

    Basic CSS selectors including: `*` (universal selector), `>` (child selector), `:first-child`, `:link`, `:visited`, `:active`, `:hover`, `:focus`, `:lang()`, `+` (adjacent sibling selector), `[attr]`, `[attr="val"]`, `[attr~="val"]`, `[attr|="bar"]`, `.foo` (class selector), `#foo` (id selector)

  8. CSS3 selectors

    Advanced element selection using selectors including: `[foo^="bar"]`, `[foo$="bar"]`, `[foo*="bar"]`, `:root`, `:nth-child()`, `:nth-last-child()`, `:nth-of-type()`, `:nth-last-of-type()`, `:last-child`, `:first-of-type`, `:last-of-type`, `:only-child`, `:only-of-type`, `:empty`, `:target`, `:enabled`, `:disabled`, `:checked`, `:not()`, `~` (general sibling)

  9. ::selection CSS pseudo-element

    The ::selection CSS pseudo-element applies rules to the portion of a document that has been highlighted (e.g., selected with the mouse or another pointing device) by the user.

  10. Directory selection from file input

    The `webkitdirectory` attribute on the `<input type="file">` element allows entire directory with file contents (and any subdirectories) to be selected.

  11. Multiple file selection

    Allows users to select multiple files in the file picker.

  12. Selection controls for input & textarea

    Controls for setting and getting text selection via `setSelectionRange()` and the `selectionStart` & `selectionEnd` properties.

  13. querySelector/querySelectorAll

    Method of accessing DOM elements using CSS selectors

  14. Selection API

    API for accessing selected content of a document, including the `window.getSelection()` method, as well as the `selectstart` & `selectionchange` events on `document`.

  15. Selectlist - Customizable select element

    Proposal for a customizable `<select>` element, currently defined as `<selectlist>`, previously `<selectmenu>`.

  16. CSS user-select: none

    Method of preventing text/element selection using CSS.

  17. selection api

  18. selection api: addrange

  19. selection api: collapse

  20. selection api: extend

  21. selection api: focusnode

  22. selection api: modify

  23. selection api: tostring

  24. selection api: type

  25. css selector: `:active`

  26. css selector: `:blank`

  27. css selector: closed

  28. css selector: `::cue`

  29. css selector: `:empty`

  30. css selector: `:enabled`

  31. css selector: `:focus`

  32. css selector: `:future`

  33. css selector: `:host`

  34. css selector: `:host()`

  35. css selector: `:hover`

  36. css selector: `:lang()`

  37. css selector: `:link`

  38. css selector: `:modal`

  39. css selector: `:muted`

  40. css selector: open

  41. css selector: `::part`

  42. css selector: `:past`

  43. css selector: `:paused`

  44. css selector: `:playing`

  45. css selector: `:root`

  46. css selector: `:scope`

  47. css selector: `:stalled`

  48. css selector: `:target`

  49. css selector: `:valid`

  50. html element: select