回文数

/**
 * @param {number} x
 * @return {boolean}
 */
var isPalindrome = function(x) {
    if (x < 0) {
        return false;
    }

    let num = x;
    let cur = 0;

    while (num !== 0) {
        cur = cur * 10 + num % 10
        num = Math.floor(num/10);
    }

    return x === cur;
};