1. DOM manipulation convenience methods

    jQuery-like methods on DOM nodes to insert nodes around or within a node, or to replace one node with another. These methods accept any number of DOM nodes or HTML strings as arguments. Includes: `ChildNode.before`, `ChildNode.after`, `ChildNode.replaceWith`, `ParentNode.prepend`, and `ParentNode.append`.

  2. Feature Policy

    This specification defines a mechanism that allows developers to selectively enable and disable use of various browser features and APIs. Feature Policy is deprecated and has been replaced with [Permissions Policy](/permissions-policy) and [Document Policy](/document-policy).

  3. Fetch

    A modern replacement for XMLHttpRequest.

  4. Session history management

    Method of manipulating the user's browser's session history in JavaScript using `history.pushState`, `history.replaceState` and the `popstate` event.

  5. Mutation events

    Deprecated mechanism for listening to changes made to the DOM, replaced by Mutation Observers.

  6. Mutation Observer

    Method for observing and reacting to changes to the DOM. Replaces MutationEvents, which is deprecated.

  7. Scoped attribute

    Deprecated method of allowing scoped CSS styles using a "scoped" attribute. Now [removed from the specification](https://github.com/whatwg/html/issues/552) and replaced by the [@scope CSS rule](/css-cascade-scope).

  8. WebVR API

    API for accessing virtual reality (VR) devices, including sensors and head-mounted displays. Replaced by the [WebXR Device API](/webxr).

  9. animation api: replacestate

  10. characterdata api: replacedata

  11. characterdata api: replacewith

  12. cssstylesheet api: replace

  13. cssstylesheet api: replacesync

  14. documentfragment api: replacechildren

  15. documenttype api: replacewith

  16. document api: replacechildren

  17. domtokenlist api: replace

  18. domtokenlist api: replace: `return()`'s value is a boolean, not void as it used to be.

  19. element api: replacechildren

  20. element api: replacewith

  21. fetchevent api: replacesclientid

  22. history api: replacestate

  23. history api: replacestate: whether the `unused` parameter is used

  24. location api: replace

  25. navigator api: deprecatedreplaceinurn

  26. node api: replacechild

  27. rtcrtpsender api: `replacetrack()`

  28. svglengthlist api: replaceitem

  29. svgnumberlist api: replaceitem

  30. svgpointlist api: replaceitem

  31. svgstringlist api: replaceitem

  32. svgtransformlist api: replaceitem

  33. css property: content: element replacement

  34. css property: resize: support on block level, replaced, table cell, or inline block elements

  35. javascript built-in: regexp: @@replace

  36. javascript built-in: string: replace

  37. javascript built-in: string: replaceall

  38. javascript built-in: symbol: replace

  39. ssl (secure sockets layer)

  40. ecmascript 2021 (es12)