var longestPalindrome = function(s) {
let start, end, result = 0;
for(let i=0; i < s.length; i++) {
let tempStart = i;
let tempEnd = i;
while(s[tempEnd] === s[tempEnd+1]) tempEnd++;
while(tempStart >= 0 && tempEnd < s.length && s[tempStart-1] == s[tempEnd+1]) {
tempStart--;
tempEnd++
}
if(result < tempEnd - tempStart+1) {
result = tempEnd - tempStart+1;
start = tempStart;
end = tempEnd;
}
}
return s.substring(start, end+1);
};