Write a program to remove palindromic subsequences from string

The problem:

You are given a string s consisting only of the letters ‘a’ and ‘b’. In a single step, you can remove one palindromic subsequence from s.

Return the minimum number of steps to make the given string empty.

A string is a subsequence of a given string if it is generated by deleting some characters of a given string without changing its order. Note that a subsequence does not necessarily need to be contiguous.

A string is called palindrome if is one that reads the same backward as well as forward.

Example #1

Input: s = "ababa"
Output: 1
Explanation: s is already a palindrome, so its entirety can be removed in a single step.

Example #2

Input: s = "abb"
Output: 2
Explanation: "abb" -> "bb" -> "". 
Remove palindromic subsequence "a" then "bb".

Example #3

Input: s = "baabb"
Output: 2
Explanation: "baabb" -> "b" -> "". 
Remove palindromic subsequence "baab" then "b".

The solution

 const removePalindromeSub = (s) => {
     if (!s) {
         return 0;
     }
     let i = 0;
     let j = s.length - 1;

     while (i < j) {
         if (s[i] === s[j]) {
             i++;
             j--;
         } else {
             return 2;
         }
     }
     return 1;
 }

 console.log(removePalindromeSub('aaaabaaaa'));