Generic constraints ensure type parameters meet specific requirements. Here's how to use them.
Basic Constraints
Loading code block...
keyof Constraint
Loading code block...
Constructor Constraints
Loading code block...
Recursive Constraints
Loading code block...
Conditional Constraints
Loading code block...
Default Type Parameters
Loading code block...
Function Overloads with Generics
Loading code block...
Mapped Type Constraints
Loading code block...
Variance and Constraints
Loading code block...
Complex Constraints
Loading code block...
Best Practices
Design:
✓ Use minimal constraints
✓ Prefer interfaces over type literals
✓ Document constraint requirements
✓ Use meaningful type parameter names
Patterns:
✓ keyof for property access
✓ extends for structural constraints
✓ Conditional types for flexibility
✓ Default parameters for convenience
Avoid:
✗ Over-constraining generics
✗ Complex nested constraints
✗ Circular type references
✗ any in constraints
Testing:
✓ Test with edge cases
✓ Verify error messages
✓ Check inference results
✓ Test with unknown types
Conclusion
Generic constraints ensure type safety while maintaining flexibility. Use extends for structural requirements, keyof for property access, and conditional types for advanced logic. Keep constraints minimal and document complex requirements.