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. JavaScript built-in: Object: defineProperty

  3. JavaScript built-in: Proxy: handler: defineProperty

  4. JavaScript built-in: Reflect: defineProperty