[LeetCode][JavaScript]Reverse Linked List

 1 /**
 2  * Definition for singly-linked list.
 3  * function ListNode(val) {
 4  *     this.val = val;
 5  *     this.next = null;
 6  * }
 7  */
 8 /**
 9  * @param {ListNode} head
10  * @return {ListNode}
11  */
12 var reverseList = function(head) {
13     if(!head || !head.next){
14         return head;
15     }
16 
17     var res = new ListNode(-1);
18     res.next = head;
19     head = head.next;
20     res.next.next = null;
21     while(head){
22         var tmp = head.next;
23         head.next = res.next;
24         res.next = head;
25         head = tmp;
26     }
27 
28     return res.next;
29 };