function Foo(x) {
  this.x = x;
  return { x: x * 2 };
}

function Bar(x) {
  this.x = x;
  return 42;
}

const f = new Foo(5);
const b = new Bar(5);

console.log(f.x, b.x, f instanceof Foo, b instanceof Bar);

function* inner() {
  yield 1;
  yield 2;
  return 100;
}

function* outer() {
  const result = yield* inner();
  yield result;
  yield 3;
}

const it = outer();
console.log(it.next().value, it.next().value, it.next().value, it.next().value);

class Base {
  static count = 0;
  static increment() {
    this.count++;
    return this.count;
  }
}

class Derived extends Base {
  static count = 10;
}

console.log(Base.increment(), Derived.increment(), Base.count, Derived.count);

let counter = 0;
const mod = {
  get counter() { return counter; },
  increment() { counter++; }
};

const { counter: snapshotCounter } = mod;
mod.increment();
mod.increment();

console.log(snapshotCounter, mod.counter, counter);

const obj = {
  value: 42,
  getValue() { return this?.value; },
  getValueArrow: () => this?.value
};
const { getValue, getValueArrow } = obj;
console.log(obj.getValue(), getValue(), obj.getValueArrow(), getValueArrow());

class Base {
  value = 10;
  getValue = () => this.value;
  constructor() {
    this.value = 20;
  }
}

class Derived extends Base {
  value = 30;
}

const d = new Derived();
console.log(d.getValue(), d.value);