1. 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.

  2. 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.

  3. Import maps

    Import maps allow control over what URLs get fetched by JavaScript `import` statements and `import()` expressions.

  4. javascript built-in: array: flatmap

  5. javascript built-in: array: map

  6. javascript built-in: iterator: flatmap

  7. javascript built-in: iterator: map

  8. javascript built-in: map

  9. javascript built-in: map: @@iterator

  10. javascript built-in: map: @@species

  11. javascript built-in: map: clear

  12. javascript built-in: map: delete

  13. javascript built-in: map: entries

  14. javascript built-in: map: foreach

  15. javascript built-in: map: get

  16. javascript built-in: map: groupby

  17. javascript built-in: map: has

  18. javascript built-in: map: keys

  19. javascript built-in: map: key equality for -0 and 0

  20. javascript built-in: map: `map()` constructor

  21. javascript built-in: map: `map()` constructor: `new map(iterable)`

  22. javascript built-in: map: `map()` constructor: `map()` without `new` throws

  23. javascript built-in: map: `map()` constructor: `new map(null)`

  24. javascript built-in: map: set

  25. javascript built-in: map: size

  26. javascript built-in: map: values

  27. javascript built-in: typedarray: map

  28. javascript built-in: weakmap

  29. javascript built-in: weakmap: delete

  30. javascript built-in: weakmap: get

  31. javascript built-in: weakmap: has

  32. javascript built-in: weakmap: set

  33. javascript built-in: weakmap: non-registered symbols as keys

  34. javascript built-in: weakmap: `weakmap()` constructor

  35. javascript built-in: weakmap: `weakmap()` constructor: `new weakmap(iterable)`

  36. javascript built-in: weakmap: `weakmap()` constructor: `weakmap()` without `new` throws

  37. javascript built-in: weakmap: `weakmap()` constructor: `new weakmap(null)`