js functional palindrome

palindrome.js

const pal = (s) => s
  .split('')
  .reduce((acc, c, head, arr) => Object.assign({}, acc, {
    tail: acc.tail - 1,
    result: (acc.result === false || arr[head] !== arr[acc.tail]) ? false : true
  }), {result: null, tail: s.length - 1})
  .result