LC 7. Reverse Integer

function reverse(x: number): number {
  let reverse = 0
  let sign = x < 0 ? -1 : 1
  x = Math.abs(x)
  let num = x
  let reverseExp = 0
  for (let i = x.toString().length - 1; i >= 0; i--) {
    const digit = Math.floor(num / 10 ** i)
    reverse += digit * 10 ** reverseExp
    num -= digit * 10 ** i
    reverseExp++
  }
  const answer = sign * reverse
  if ((-2) ** 31 > answer || answer > 2 ** 31) {
    return 0
  }
  return answer
}