WeakMap and WeakSet hold weak references to objects, enabling garbage collection. Here's how to use them.
WeakMap vs Map
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WeakSet vs Set
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Private Data Pattern
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Caching with WeakMap
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DOM Element Metadata
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Object Visited Tracking
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WeakRef for Optional Caching
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Instance Counting
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React Integration
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API Response Caching
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Best Practices
Use WeakMap when:
✓ Storing metadata for objects
✓ Implementing private data
✓ Caching computed values
✓ Associating data with DOM elements
Use WeakSet when:
✓ Tracking visited objects
✓ Marking objects as processed
✓ Checking object membership
✓ Preventing duplicate processing
Avoid when:
✗ Need to iterate over entries
✗ Need to know size
✗ Keys are primitives
✗ Need persistent storage
Conclusion
WeakMap and WeakSet enable memory-efficient object associations. Use WeakMap for private data, caching, and metadata. Use WeakSet for tracking processed objects. Both automatically clean up when objects are garbage collected, preventing memory leaks.