A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters, it reads the same forward and backward. Alphanumeric characters include letters and numbers.

Given a string s, return true if it is a palindrome, or false otherwise.

var isPalindrome = function(s) {
    s = s.toLowerCase().replace(/[^a-z0-9]/g, '')
    let mainIndex = 0;
    while(mainIndex < s.length / 2) {
        if (s[mainIndex] !== s[s.length - mainIndex - 1]) {
            return false;
        }
        mainIndex++
    }
    return true
};