1. Asynchronous Clipboard API

    A modern, asynchronous Clipboard API based on Promises

  2. Async functions

    Async functions make it possible to treat functions returning Promise objects as if they were synchronous.

  3. Beacon API

    Allows data to be sent asynchronously to a server with `navigator.sendBeacon`, even after a page was closed. Useful for posting analytics data the moment a user was finished using the page.

  4. IntersectionObserver

    API that can be used to understand the visibility and position of DOM elements relative to a containing element or to the top-level viewport. The position is delivered asynchronously and is useful for understanding the visibility of elements and implementing pre-loading and deferred loading of DOM content.

  5. Promises

    A promise represents the eventual result of an asynchronous operation.

  6. 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.

  7. extendableevent api: waituntil: `waituntil` may be called asynchronously

  8. filesystemdirectoryhandle api: @@asynciterator

  9. htmlscriptelement api: async

  10. sourcebuffer api: appendbufferasync

  11. sourcebuffer api: removeasync

  12. xmldocument api: async

  13. javascript built-in: asyncfunction

  14. javascript built-in: asyncgenerator

  15. javascript built-in: asyncgeneratorfunction

  16. javascript built-in: asyncgenerator: next

  17. javascript built-in: asyncgenerator: return

  18. javascript built-in: asyncgenerator: throw

  19. javascript built-in: asynciterator

  20. javascript built-in: asynciterator: @@asynciterator

  21. javascript built-in: atomics: waitasync

  22. javascript built-in: symbol: asynciterator

  23. javascript function: method definitions: async generator methods

  24. javascript function: method definitions: async methods

  25. javascript operator: `async function` expression

  26. javascript operator: `async function*` expression

  27. javascript operator: await

  28. javascript operator: await: use at module top level

  29. javascript statement: `async function*` statement

  30. ecmascript 2018 (es9)