LC 234. Palindrome Linked List

/**
 * Definition for singly-linked list.
 * function ListNode(val, next) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.next = (next===undefined ? null : next)
 * }
 */
/**
 * @param {ListNode} head
 * @return {boolean}
 */
var isPalindrome = function (head) {
  const vals = []
  while (head !== null) {
    vals.push(head.val)
    head = head.next
  }
  for (let i = 0, j = vals.length - 1; i < j; ++i, --j) {
    if (vals[i] !== vals[j]) return false
  }
  return true
};