add #9

+/**
+ * @param {number} x
+ * @return {boolean}
+ */
+var isPalindrome = function(x) {
+    if (x < 0 || (!!x && x % 10 === 0)) {
+        return false;
+    }
+
+    let reverseNum = 0;
+    while (x > reverseNum) {
+        reverseNum = reverseNum * 10 + x % 10;
+        x = ~~(x/10);
+    }
+    // console.info(x, reverseNum);
+    return x === reverseNum || x === ~~(reverseNum/10);
+};
+
+let nums = [0, 10, 121, 1001, 10001, 12021, 12212];
+nums.forEach(n => {
+    console.info(n, isPalindrome(n));
+});

@@ -12,7 +12,7 @@ leetcode-cn.com上的题库代码实现
 |                             | 6     | [Z 字形变换](https://leetcode-cn.com/problems/zigzag-conversion) | **中等** |
 | 7-reverse.js                | 7     | [整数反转](https://leetcode-cn.com/problems/reverse-integer) | **简单** |
 |                             | 8     | [字符串转换整数 (atoi)](https://leetcode-cn.com/problems/string-to-integer-atoi) | **中等** |
-|                             | 9     | [回文数](https://leetcode-cn.com/problems/palindrome-number) | **简单** |
+| 9-isPalindrome.js           | 9     | [回文数](https://leetcode-cn.com/problems/palindrome-number) | **简单** |
 |                             | 10    | [正则表达式匹配](https://leetcode-cn.com/problems/regular-expression-matching) | **困难** |
 |                             | 11    | [盛最多水的容器](https://leetcode-cn.com/problems/container-with-most-water) | **中等** |
 |                             | 12    | [整数转罗马数字](https://leetcode-cn.com/problems/integer-to-roman) | **中等** |