9. Palindrome Number

Description:

Determine whether an integer is a palindrome. Do this without extra space.
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My code:

/**
 * @param {number} x
 * @return {boolean}
 */
var isPalindrome = function(x) {
    var str = x.toString();
    if(x >= 0) {
        var reverseNum = parseInt(str.split("").reverse().join(""));
         if(reverseNum == x) {
            return true;
         } else {
            return false;
         }
    } else {
        return false;
    }
   
};

Note: 负数全部不算回文数；刚开始不知道without extra space是什么意思，看了github的issue才了解到应该是指复杂度应为1，用js的话感觉还是比较容易做的