JSFiddle - React, Tailwind, and code Playground

JavaScript

function isPalindrome(s,i) {
 return(i=i||0)<0||i>=s.length>>1||s[i]==s[s.length-1-i]&&isPalindrome(s,++i);
}
console.log(isPalindrome('test'));
console.log(isPalindrome('racecar'));