TIL2.LeetCode_Reverse Integer

Given a signed 32-bit integer x, return x with its digits reversed.
If reversing x causes the value to go outside the signed 32-bit integer range [−231, 231 − 1], then return 0.
Assume the environment does not allow you to store 64-bit integers(signed or unsigned).
Example 1:
Input: x =123
Output:321
Example 2:
Input: x = -123
Output:-321
Example 3:
Input:x=120
Output:21
Example 4:
Input:x=0
Output:0
1.toString()を使用してnumberをstringに変換します.
2.文字列を反転します.
3.逆さまの文字列をnumberに再変換します.

function reverseInt(n) {
  const reversed = n.toString().split('').reverse().join('');
  return Math.sign(n)*parseInt(reversed);
}

Math.signは負の数-1を返し、正の値は1を返し、0は0を返します.
inputが-の場合、出力も-に戻る必要があります.看板を使えばいい.