Proxy handlers intercept operations on objects, enabling powerful meta-programming patterns. Here's how to use each trap effectively.
Basic Structure
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get Trap
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set Trap
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has Trap
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deleteProperty Trap
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ownKeys Trap
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apply Trap (Functions)
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construct Trap (Classes)
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getOwnPropertyDescriptor Trap
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defineProperty Trap
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getPrototypeOf / setPrototypeOf Traps
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isExtensible / preventExtensions Traps
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Complete Observable Object
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Best Practices
Trap Usage:
✓ Use Reflect methods for defaults
✓ Return correct values
✓ Maintain invariants
✓ Handle edge cases
Performance:
✓ Keep handlers simple
✓ Cache proxies when possible
✓ Avoid deep nesting
✓ Consider alternatives for hot paths
Patterns:
✓ Validation and access control
✓ Logging and debugging
✓ Observable objects
✓ Default values
Avoid:
✗ Breaking object invariants
✗ Infinite recursion
✗ Hiding errors silently
✗ Over-engineering simple cases
Conclusion
Proxy handlers provide fine-grained control over object operations through traps like get, set, has, and deleteProperty. Always use Reflect methods to maintain default behavior and return appropriate values. Proxies are powerful for validation, observation, access control, and virtualization patterns, but should be used judiciously as they add overhead and complexity.