javascript function for determining if a string is a palindrome.

isPalindrome.js

var isPalindrome = (input) => {
  if (typeof input !== 'string' && !Array.isArray(input)) { throw "isPalindrome() requires a string or array as an argument."; }
  if (typeof input === 'string') { input = input.split(""); }
  let one = input.pop(); 
  let two = input.shift(); 
  if (two === undefined) { return true; } 
  if ( one === two ) { return isPalindrome(input); } 
  return false; 
}
console.log(isPalindrome('a')); // true
console.log(isPalindrome('aa')); //true
console.log(isPalindrome('aad')); //false
console.log(isPalindrome('aada')); //false
console.log(isPalindrome('aadaa')); //true
console.log(isPalindrome('aaddaa')); //true