最长回文子串 - LeetCode

 题目：
 
 给定一个字符串 s，找到 s 中最长的回文子串。你可以假设 s 的最大长度为1000。
 
 示例 1：
 输入: "babad"
 输出: "bab"
 注意: "aba"也是一个有效答案。
 
 示例 2：
 输入: "cbbd"
 输出: "bb"
 

 解题思路：待更新
  
 答案：
 

/**
 * @param {string} s = "123456"
 * @return {string}
 */
var s = "civilwartestingwhetherthatnaptionoranynartionsoconceivedandsodedicatedcanlongendureWeareqmetonagreatbattlefiemldoftzhatwarWehavecometodedicpateaportionofthatfieldasafinalrestingplaceforthosewhoheregavetheirlivesthatthatnationmightliveItisaltogetherfangandproperthatweshoulddothisButinalargersensewecannotdedicatewecannotconsecratewecannothallowthisgroundThebravelmenlivinganddeadwhostruggledherehaveconsecrateditfaraboveourpoorponwertoaddordetractTgheworldadswfilllittlenotlenorlongrememberwhatwesayherebutitcanneverforgetwhattheydidhereItisforusthelivingrathertobededicatedheretotheulnfinishedworkwhichtheywhofoughtherehavethusfarsonoblyadvancedItisratherforustobeherededicatedtothegreattdafskremainingbeforeusthatfromthesehonoreddeadwetakeincreaseddevotiontothatcauseforwhichtheygavethelastpfullmeasureofdevotionthatweherehighlyresolvethatthesedeadshallnothavediedinvainthatthisnationunsderGodshallhaveanewbirthoffreedomandthatgovernmentofthepeoplebythepeopleforthepeopleshallnotperishfromtheearth";
var longestPalindrome = function (s) {

    var newS = "#", strLong = "", str;
    for (let m in s) {
        newS += s[m] + "#";
    }
    for (var i = 1; i < newS.length; i++) {
        str = newS[i];
        for (var j = 1; j < newS.length; j++) {
            if(newS[i - j] == undefined || newS[i + j] == undefined) {
                break;
            }
            if (newS[i - j] == newS[i + j]) {
                str = newS[i - j] + str + newS[i - j];
            } else {
                break;
            }
        }
        if (str.length > strLong.length) {
            strLong = str;
        }
    }
    return strLong.replace(/#/g,'');
};