Check if a string is a valid palindrome

Valid-Palindrome.php

<?php
class Solution {

    /**
     * @param String $s
     * @return Boolean
     */
    function isPalindrome($s) {
        if(! isset($s)) return false;
        
        
        $s = strtolower($s);        
        $s = preg_replace("/[\W]/","", $s);
        
        return strrev($s) == $s;
    
    }
}

ValidPalindrome.js

/**
 * @param {string} s
 * @return {boolean}
 */
var isPalindrome = function(s) {
    
    if(!s) return false;
    
    s = s.toLowerCase().replace(/\W+/g,'')
    
    return s == s.split('').reverse().join('')
    
};