Run results for: Map.get() !== undefined VS Map.has() + .get()
Performance comparison of Map.get() !== undefined to check if element exists and Map.has() as most of the time you need the element after the .has() check anyway.
LIMITATION: The checks are not completely the same. If the map contains a key whose value is intentionally set to undefined (Map.set(1, undefined)), .has() will return true, while the .get() !== undefined will be false.