Task #5 can be solved in a simpler way

[Andrey123815]

var longestPalindrome = function(s) {
let start = 0, end = 0, len = s.length;

for (let i = 0 ; i < len; ++i) {
    let maxAvailableLength = maxPalindrLenAroundCenter(s, i, i);
    if (maxAvailableLength > end - start + 1) {
        start = i - Math.floor(maxAvailableLength / 2);
        end = start + maxAvailableLength - 2;
    }
}

return s.slice(start, end + 1);

};

var maxPalindrLenAroundCenter = function (s, l, r) {
while(l > 0 && r < s.length - 1 && s[l] === s[r]) {
l--;
r++;
}

return r - l;

};