console.log(typeof NaN);
console.log(NaN === NaN);

async function test() {
  console.log(1);
  await new Promise(resolve => setTimeout(resolve, 1000));
  console.log(2);
  return 3;
}

console.log(4);
test().then(console.log);
console.log(5);

function Animal(name) {
  this.name = name;
}
Animal.prototype.sound = 'Generic sound';

const dog = new Animal('Dog');

Animal.prototype.sound = 'Bark';
console.log(dog.sound);

const obj = {
  value: 10,
  getValue: function () {
    return () => this.value;
  }
};

const value = 20;
const getValue = obj.getValue();
console.log(getValue());

console.log(typeof null);
console.log(typeof function () {});

console.log('A');

setTimeout(() => console.log('B'), 0);

Promise.resolve()
  .then(() => {
    console.log('C');
    return Promise.resolve();
  })
  .then(() => console.log('D'));

console.log('E');

function memoize(fn) {
  const cache = {};
  return (arg) => cache[arg] ?? (cache[arg] = fn(arg));
}

const square = memoize((n) => n * n);

console.log(square(5)); 
console.log(square(5)); 
console.log(square(6));