1
var reverse = function (x) {
2
  let val = Math.abs(x);
3
  let res = 0;
4
  while (val != 0) {
5
    res = res * 10 + (val % 10);
6
    val = Math.floor(val / 10);
7
  }
8
  if (x < 0) res = 0 - res;
9
  return res > 2 ** 31 - 1 || res < (-2) ** 31 ? 0 : res;
10
};