Merge Two Sorted Linked Lists in Javascript

Problem :

Given list l1 = 1->2->3. And list l2 = 10->20->30. Generate a new list mergedList = 1->2->3->10->20->30.

Given list l1 = 1->3->4. And list l2 = 1->2->3. Generate a new list mergedList = 1->2->3->3->4.

Solution :

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