1. Array.prototype.find

    The `find()` method returns the value of the first item in the array based on the result of the provided testing function.

  2. Array.prototype.findIndex

    The `findIndex()` method returns the index of the first element in the array that satisfies the provided testing function.

  3. flat & flatMap array methods

    Methods to flatten any sub-arrays found in an array by concatenating their elements.

  4. Array.prototype.includes

    Determines whether or not an array includes the given value, returning a boolean value (unlike `indexOf`).

  5. Date.prototype.toLocaleDateString

    Date method to generate a language sensitive representation of a given date, formatted based on a specified locale and options.

  6. Scroll methods on elements (scroll, scrollTo, scrollBy)

    Methods to change the scroll position of an element. Similar to setting `scrollTop` & `scrollLeft` properties, but also allows options to be passed to define the scroll behavior.

  7. ECMAScript 5

    Full support for the ECMAScript 5 specification. Features include `Function.prototype.bind`, Array methods like `indexOf`, `forEach`, `map` & `filter`, Object methods like `defineProperty`, `create` & `keys`, the `trim` method on Strings and many more.

  8. ECMAScript 2015 (ES6)

    Support for the ECMAScript 2015 specification. Features include Promises, Modules, Classes, Template Literals, Arrow Functions, Let and Const, Default Parameters, Generators, Destructuring Assignment, Rest & Spread, Map/Set & WeakMap/WeakSet and many more.

  9. String.prototype.includes

    The includes() method determines whether one string may be found within another string, returning true or false as appropriate.

  10. String.prototype.padStart(), String.prototype.padEnd()

    The `padStart()` and `padEnd()` methods pad the current string with a given string (eventually repeated) so that the resulting string reaches a given length. The pad is applied from the start (left) of the current string for `padStart()`, and applied from the end (right) of the current string for `padEnd()`.

  11. Promise.prototype.finally

    When the promise is settled, whether fulfilled or rejected, the specified callback function is executed.

  12. javascript built-in: function: tostring: implements `function.prototype.tostring` revision

  13. javascript built-in: object: getprototypeof

  14. javascript built-in: object: isprototypeof

  15. javascript built-in: object: setprototypeof

  16. javascript built-in: proxy: handler: getprototypeof

  17. javascript built-in: proxy: handler: setprototypeof

  18. javascript built-in: reflect: getprototypeof

  19. javascript built-in: reflect: setprototypeof

  20. javascript built-in: regexp: global: prototype accessor property (es2015)

  21. javascript built-in: regexp: ignorecase: prototype accessor property (es2015)

  22. javascript built-in: regexp: multiline: prototype accessor property (es2015)

  23. javascript built-in: regexp: source: prototype accessor property (es2015)

  24. javascript built-in: regexp: sticky: prototype accessor property (es2015)

  25. javascript built-in: symbol: tostringtag: `tostringtag` available on all dom prototype objects

  26. javascript built-in: typedarray: indexed properties not consulting prototype

  27. ecmascript 2016 (es7)

  28. ecmascript 2018 (es9)

  29. ecmascript 2019 (es10)