const order = [];
order.push('start');
setTimeout(() => { order.push('timeout'); console.log(order.join(',')); }, 0);
Promise.resolve().then(() => order.push('promise1'));
async function foo() {
  order.push('foo start');
  await null;
  order.push('foo end');
}
foo();
Promise.resolve().then(() => order.push('promise2'));
order.push('end');

const message = 'a😀bc';
const codePoints = [...message];
const combined = {
  raw: message.length,
  points: codePoints.length,
  second: codePoints[1]
};
console.log(combined.raw, combined.points, combined.second);

class Counter {
  #count = 0;
  static #instances = 0;
  constructor() { Counter.#instances++; }
  #increment() { this.#count++; }
  incrementAndGet() {
    this.#increment();
    return this.#count;
  }
  static get total() { return Counter.#instances; }
}

class SpecialCounter extends Counter {
  incrementAndGet() {
    return super.incrementAndGet() * 2;
  }
}

const c1 = new Counter();
const c2 = new SpecialCounter();
console.log(`${c1.incrementAndGet()} ${c2.incrementAndGet()} ${Counter.total}`);

const arr = [1, 2, 3];
const log = [];
const result = arr.map((x, i) => {
  if (i === 0) arr.push(4);
  log.push(x);
  return x * 2;
});
console.log(result.join(','), log.join(','), arr.join(','));

const compose = (...fns) => fns.reduce((f, g) => (...args) => f(g(...args)));
const pipe = (...fns) => fns.reduce((f, g) => (...args) => g(f(...args)));

const add1 = x => x + 1;
const double = x => x * 2;
const square = x => x * x;

const composed = compose(square, double, add1);
const piped = pipe(square, double, add1);

console.log(composed(3), piped(3));