LC 234. Palindrome Linked List

 1/**
 2 * Definition for singly-linked list.
 3 * function ListNode(val, next) {
 4 *     this.val = (val===undefined ? 0 : val)
 5 *     this.next = (next===undefined ? null : next)
 6 * }
 7 */
 8/**
 9 * @param {ListNode} head
10 * @return {boolean}
11 */
12var isPalindrome = function (head) {
13  const vals = []
14  while (head !== null) {
15    vals.push(head.val)
16    head = head.next
17  }
18  for (let i = 0, j = vals.length - 1; i < j; ++i, --j) {
19    if (vals[i] !== vals[j]) return false
20  }
21  return true
22};