mergeTwoLinkedLists.js

// Definition for singly-linked list:
// function ListNode(x) {
//   this.value = x;
//   this.next = null;
// }
//
function mergeTwoLinkedLists(l1, l2) {
  const list = [];
  let left = l1;
  let right = l2;
  while (left || right) {
    if (left && right) {
      if (left.value < right.value) {
        list.push(left.value);
        left = left && left.next;
      } else {
        list.push(right.value);
        right = right && right.next;
      }
    } else if (left && !right) {
      list.push(left.value);
      left = left && left.next;
    } else if (right && !left) {
      list.push(right.value);
      right = right && right.next;
    }
  }
  
  return list;
}