1. Scoped Styles: the @scope rule

    Allows CSS rules to be scoped to part of the document, with upper and lower limits described by selectors.

  2. CSS clip-path property (for HTML)

    Method of defining the visible region of an HTML element using SVG or a shape definition.

  3. CSS Filter Effects

    Method of applying filter effects using the `filter` property to elements, matching filters available in SVG. Filter functions include blur, brightness, contrast, drop-shadow, grayscale, hue-rotate, invert, opacity, sepia and saturate.

  4. :focus-within CSS pseudo-class

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

  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. disabled attribute of the fieldset element

    Allows disabling all of the form control descendants of a fieldset via a `disabled` attribute on the fieldset element itself.

  7. CSS font-smooth

    Controls the application of anti-aliasing when fonts are rendered.

  8. Input Method Editor API

    Provides scripted access to the Input Method Editor (IME). An IME is often used to input characters from East Asian languages by typing roman characters and selecting from the resulting suggestions.

  9. Minimum length attribute for input fields

    Declares a lower bound on the number of characters a user can input.

  10. Element.insertAdjacentHTML()

    Inserts a string of HTML into a specified position in the DOM relative to the given element.

  11. maxlength attribute for input and textarea elements

    Declares an upper bound on the number of characters the user can input. Normally the UI ignores attempts by the user to type in additional characters beyond this limit.

  12. theme-color Meta Tag

    Meta tag to define a suggested color that browsers should use to customize the display of the page or of the surrounding user interface. The meta tag overrides any theme-color set in the web app manifest.

  13. Ogg/Theora video format

    Free lossy video compression format.

  14. Path2D

    Allows path objects to be declared on 2D canvas surfaces

  15. Web Bluetooth

    Allows web sites to communicate over GATT with nearby user-selected Bluetooth devices in a secure and privacy-preserving way.

  16. Web Authentication API

    The Web Authentication API is an extension of the Credential Management API that enables strong authentication with public key cryptography, enabling password-less authentication and / or secure second-factor authentication without SMS texts.

  17. abortsignal api: throwifaborted

  18. dynamicscompressornode api: threshold

  19. htmltableelement api: thead

  20. idbindex api: name: renaming through `name` setter

  21. intersectionobserver api: thresholds

  22. html element: meta: name: theme-color

  23. html element: th

  24. html element: thead

  25. html element: thead: align

  26. html element: thead: bgcolor

  27. html element: thead: char

  28. html element: thead: charoff

  29. html element: thead: valign

  30. html element: th: abbr

  31. html element: th: align

  32. html element: th: axis

  33. html element: th: bgcolor

  34. html element: th: char

  35. html element: th: charoff

  36. html element: th: colspan

  37. html element: th: headers

  38. html element: th: rowspan

  39. html element: th: scope

  40. html element: th: valign

  41. manifest: theme_color

  42. javascript built-in: generator: throw

  43. javascript operator: greater than (`a > b`)

  44. javascript operator: greater than or equal (`a >= b`)

  45. javascript operator: less than (`a < b`)

  46. javascript operator: less than or equal (`a <= b`)

  47. javascript operator: this

  48. javascript statement: throw

  49. the react javascript library

  50. the vue.js framework