1. CSS background-attachment

    Method of defining how a background image is attached to a scrollable element. Values include `scroll` (default), `fixed` and `local`.

  2. background-position-x & background-position-y

    CSS longhand properties to define x or y positions separately.

  3. CSS background-repeat round and space

    Allows CSS background images to be repeated without clipping.

  4. CSS3 Border-radius (rounded corners)

    Method of making the border corners round. Covers support for the shorthand `border-radius` as well as the long-hand properties (e.g. `border-top-left-radius`)

  5. BroadcastChannel

    BroadcastChannel allows scripts from the same origin but other browsing contexts (windows, workers) to send each other messages.

  6. Brotli Accept-Encoding/Content-Encoding

    More effective lossless compression algorithm than gzip and deflate.

  7. Basic console logging functions

    Method of outputting data to the browser's console, intended for development purposes.

  8. CSS Backdrop Filter

    Method of applying filter effects (like blur, grayscale or hue) to content/elements below the target element.

  9. CSS background-position edge offsets

    Allows CSS background images to be positioned relative to the specified edge using the 3 to 4 value syntax. For example: `background-position: right 5px bottom 5px;` for positioning 5px from the bottom-right corner.

  10. CSS background-blend-mode

    Allows blending between CSS background images, gradients, and colors.

  11. CSS Logical Properties

    Logical properties and values provide control of layout through logical, rather than physical, direction and dimension mappings. These properties are `writing-mode` relative equivalents of their corresponding physical properties.

  12. Blending of HTML/SVG elements

    Allows blending between arbitrary SVG and HTML elements

  13. CSS text-wrap: balance

    Allows multiple lines of text to have their lines broken in such a way that each line is roughly the same width, often used to make headlines more readable and visually appealing.

  14. CSS Flexible Box Layout Module

    Method of positioning elements in horizontal or vertical stacks. Support includes all properties prefixed with `flex`, as well as `display: flex`, `display: inline-flex`, `align-content`, `align-items`, `align-self`, `justify-content` and `order`.

  15. CSS Font Loading

    This CSS module defines a scripting interface to font faces in CSS, allowing font faces to be easily created and loaded from script. It also provides methods to track the loading status of an individual font, or of all the fonts on an entire page.

  16. CSS inline-block

    Method of displaying an element as a block while flowing it with text.

  17. Lookbehind in JS regular expressions

    The positive lookbehind (`(?<= )`) and negative lookbehind (`(?<! )`) zero-width assertions in JavaScript regular expressions can be used to ensure a pattern is preceded by another pattern.

  18. KeyboardEvent.location

    A `KeyboardEvent` property that indicates the location of the key on the input device. Useful when there are more than one physical key for the same logical key (e.g. left or right "Control" key; main or numpad "1" key).

  19. Lazy loading via attribute for images & iframes

    The `loading` attribute on images & iframes gives authors control over when the browser should start loading the resource.

  20. localeCompare()

    The `localeCompare()` method returns a number indicating whether a reference string comes before or after or is the same as the given string in sort order.

  21. Web Storage - name/value pairs

    Method of storing data locally like cookies, but for larger amounts of data (sessionStorage and localStorage, used to fall under HTML5).

  22. Pointer Lock API

    API that provides access to raw mouse movement data. This is done by ignoring boundaries resulting from screen edges where the cursor can't go beyond, providing proper control for first person or real time strategy games.

  23. CSS3 word-break

    Property to prevent or allow words to be broken over multiple lines between letters.

  24. javascript built-in: atomics: load

  25. javascript built-in: intl: locale

  26. javascript built-in: intl: locale: basename

  27. javascript built-in: intl: locale: calendar

  28. javascript built-in: intl: locale: casefirst

  29. javascript built-in: intl: locale: collation

  30. javascript built-in: intl: locale: getcalendars

  31. javascript built-in: intl: locale: getcollations

  32. javascript built-in: intl: locale: gethourcycles

  33. javascript built-in: intl: locale: gettextinfo

  34. javascript built-in: intl: locale: gettimezones

  35. javascript built-in: intl: locale: getweekinfo

  36. javascript built-in: intl: locale: hourcycle

  37. javascript built-in: intl: locale: language

  38. javascript built-in: intl: locale: maximize

  39. javascript built-in: intl: locale: minimize

  40. javascript built-in: intl: locale: numeric

  41. javascript built-in: intl: locale: region

  42. javascript built-in: intl: locale: script

  43. javascript built-in: intl: locale: tostring

  44. javascript built-in: math: log

  45. javascript built-in: math: log10

  46. javascript built-in: math: log10e

  47. javascript built-in: math: log1p

  48. javascript built-in: math: log2

  49. javascript built-in: math: log2e

  50. javascript built-in: string: localecompare: `options` parameter