Leetcode 234. Palindrome Linked List javascript

/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */
/**
 * @param {ListNode} head
 * @return {boolean}
 */
var isPalindrome = function(head) {
    let datas = [];
    while(head !== null){
        datas.push(head.val);
        head = head.next;
    }
    let length = datas.length;
    for(var i = 0; i < length / 2; ++i){
        if(datas[i] !== datas[length - i - 1]){
            return false;
        }
    }
    return true;
};