function smallestCommons(arr) {
  const [min, max] = arr.sort((a, b) => a - b);
  const range = Array(max - min + 1)
    .fill(0)
    .map((_, i) => i + min);
  const gcd = (a, b) => (b === 0 ? a : gcd(b, a % b));
  const lcm = (a, b) => (a * b) / gcd(a, b);
  return range.reduce((mul, cur) => lcm(mul, cur));
}
console.log(smallestCommons([2, 10]));