【leetcode】21. Merge Two Sorted Lists

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

/** * Definition for singly-linked list. * function ListNode(val) { *     this.val = val; *     this.next = null; * } *//** * @param {ListNode} l1 * @param {ListNode} l2 * @return {ListNode} */var mergeTwoLists = function(l1, l2) {    var head = new ListNode(-1);    var new_list = head;    while(l1!==null&&l2!==null){        if(l1.val>l2.val){            new_list.next = new ListNode(l2.val);            l2 = l2.next;        }else{            new_list.next = new ListNode(l1.val);            l1 = l1.next;        }        new_list = new_list.next;    }    if(l1===null){        new_list.next = l2;    }    if(l2===null){        new_list.next = l1;    }    return head.next;};