WeakSet

Summary

Like a Set, but can only hold objects (not primitives) and holds them weakly, allowing garbage collection once nothing else references them. Its weak references make it suitable for tracking object membership without keeping those objects alive solely because they are present in the collection.

• 1Read a use case for WeakSet: tracking which objects have been 'processed' without leaking. Then apply the idea in a small example so the theory becomes practical.
• 2Compare WeakSet to Set — note WeakSet also isn't iterable. Write down when you would choose each option and what trade-off drives that choice.
• 3Understand this is a niche tool — most day-to-day code uses Set, not WeakSet.