memoization, factorial 간편 생성

const memo = (func) => {

  const memo = {};

  return index => {
    console.log('memo[index]', memo[index]);

   return memo[index] ??= func(index)
  }
}

const fac = (num) => {
  if (num < 2) {
    return 1;
  }

  return fac(num-1) * num
}

Try it

const memoFac = memo(fac);
memoFac(3)
memoFac(3)