Add Two Numbers

Problem statement

You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order, and each of their nodes contains a single digit. Add the two numbers and return the sum as a linked list.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Example 1:

Input: l1 = [2,4,3], l2 = [5,6,4]Output: [7,0,8]Explanation: 342 + 465 = 807.

Example 2:

Input: l1 = [0], l2 = [0]Output: [0]

Example 3:

Input: l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]Output: [8,9,9,9,0,0,0,1]

Constraints:

• The number of nodes in each linked list is in the range [1, 100].
• 0 <= Node.val <= 9
• It is guaranteed that the list represents a number that does not have leading zeros.

My solution

/**
 * Definition for singly-linked list.
 * function ListNode(val, next) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.next = (next===undefined ? null : next)
 * }
 */
/**
 * @param {ListNode} l1
 * @param {ListNode} l2
 * @return {ListNode}
 */
var addTwoNumbers = function(l1, l2) {
    let carry = 0;
    let link = node = new ListNode()
    
    while (l1 || l2) {
        let currSum = 0;
        
        if (l1 && l2) {
            currSum += l1.val + l2.val + carry
            
            l1 = l1.next;
            l2 = l2.next;
        } else if (l1) {
            currSum += l1.val + carry
            
            l1 = l1.next;
        } else if (l2) {
            currSum += l2.val + carry
            
            l2 = l2.next;
        }
        
        carry = Math.floor(currSum / 10);
        currSum = Math.floor(currSum % 10)
        node.next = new ListNode(currSum)
        node = node.next;
    }
    
    if (carry !== 0) {
        node.next = new ListNode(carry)
    }
    
    return link.next
};