Write a function to delete a node (except the tail) in a singly linked list, given only access to that node.

Supposed the linked list is 1 -> 2 -> 3 -> 4 and you are given the third node with value 3, the linked list should become 1 -> 2 -> 4 after calling your function.

删除一个节点，当前节点的值等于下一个节点的当前节点的下一个指向下一个的下一个。

var deleteNode = function(node) {
    node.val = node.next.val;
    node.next = node.next.next;
};