class Foo {
  static #x = 1;
  static #m = function() { return this.#x; };
  static #self = Foo;
  static self = Foo;
  static getSelf() { return this }

  static test() {
    const o = { Foo: Foo };
    const deep = { very: { o } };
    function fn() {
      return o;
    }
    function fnDeep() {
      return deep;
    }

    function f(o, r = o?.Foo.#m()) {
      return r;
    }

    function g(o, r = o?.Foo.#self.getSelf().#m()) {
      return r;
    }

    function h(fnDeep, r = fnDeep?.().very.o?.Foo?.#m()) {
      return r;
    }

    function i(fn, r = fn?.().Foo.#self?.getSelf()?.self.#m()) {
      return r;
    }

    function j(fn, r = (fn().Foo.#self.getSelf().self.#m)?.()) {
      return r;
    }

    expect(f(o)).toBe(1);
    expect(g(o)).toBe(1);
    expect(h(fnDeep)).toBe(1);
    expect(i(fn)).toBe(1);
    expect(j(fn)).toBe(1);
  }
}

Foo.test();