JavaScript WeakMap and WeakSet Guide

WeakMap and WeakSet hold weak references to objects, enabling garbage collection. Here's how to use them.

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

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.

JavaScript WeakMap and WeakSet Guide

WeakMap vs Map#

WeakSet vs Set#

Private Data Pattern#

Caching with WeakMap#

DOM Element Metadata#

Object Visited Tracking#

WeakRef for Optional Caching#

Instance Counting#

React Integration#

API Response Caching#

Best Practices#

Conclusion#

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