countSubstrings = (s, count = 0) => {
    for (let left = 0; (left < s.length); left++) {      /* Time O(N) */
        for (let right = left; (right < s.length); right++) {/* Time O(N) */
            count += Number(isPalindrome(s, left, right));      /* Time O(N) */
        }
    }

    return count;
}
Brut Force - Check All Substrings
Time O(N^3) | Space O(1)
https://leetcode.com/problems/palindromic-substrings/
@param {string} s
@return {number}