1. Explicit descendant combinator >>

    An explicit, non-whitespace spelling of the descendant combinator. `A >> B` is equivalent to `A B`.

  2. CSS Exclusions Level 1

    Exclusions defines how inline content flows around elements. It extends the content wrapping ability of floats to any block-level element.

  3. Document.execCommand()

    Allows running commands to manipulate the contents of an editable region in a document switched to designMode

  4. Encrypted Media Extensions

    The EncryptedMediaExtenstions API provides interfaces for controlling the playback of content which is subject to a DRM scheme.

  5. 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`.

  6. Intrinsic & Extrinsic Sizing

    Allows for the heights and widths to be specified in intrinsic values using the `max-content`, `min-content`, `fit-content` and `stretch` (formerly `fill`) properties.

  7. 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.

  8. Media Source Extensions

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

  9. async attribute for external scripts

    The boolean async attribute on script elements allows the external JavaScript file to run when it's available, without delaying page load first.

  10. defer attribute for external scripts

    The boolean defer attribute on script elements allows the external JavaScript file to run when the DOM is loaded, without delaying page load first.

  11. Signed HTTP Exchanges (SXG)

    Part of the Web Packaging spec, Signed HTTP Exchanges allow a different origin server to provide a resource, and this will be treated as if it came from the original server. This can be used with AMP CDNs, for example, to allow the original URL to be displayed in the URL bar.

  12. WebAssembly Sign Extension Operators

    An extension to WebAssembly adding sign-extension operator instructions

  13. extendableevent api

  14. extendableevent api: waituntil

  15. extendablemessageevent api

  16. external api

  17. ext_blend_minmax api

  18. ext_color_buffer_float api

  19. ext_disjoint_timer_query api

  20. ext_float_blend api

  21. ext_frag_depth api

  22. ext_polygon_offset_clamp api

  23. ext_srgb api

  24. javascript built-in: atomics: exchange

  25. javascript built-in: math: exp

  26. javascript built-in: math: expm1

  27. grammar: regular expression literals (`/ab+c/g`)

  28. javascript operator: exponentiation (`**`)

  29. javascript statement: export

  30. javascript statement: export: `default` keyword with `export`

  31. javascript statement: export: `export * as namespace`

  32. lookahead assertions in js regular expressions

  33. internet explorer features

  34. microsoft internet explorer