TypeScript Conditional Types Guide

Conditional types enable complex type logic based on conditions. Here's how to use them effectively.

Distributive Conditional Types#

Loading code block...

Best Practices#

Design:
✓ Use infer for extracting types
✓ Leverage distribution over unions
✓ Wrap in tuple to prevent distribution
✓ Use recursion carefully

Readability:
✓ Name complex conditions clearly
✓ Break down nested conditions
✓ Use intermediate types
✓ Document non-obvious logic

Performance:
✓ Avoid deep recursion
✓ Cache computed types
✓ Limit union size
✓ Use constraints

Avoid:
✗ Over-complicated conditions
✗ Deeply nested ternaries
✗ Unclear type logic
✗ Excessive distribution

Conditional types enable powerful type-level programming in TypeScript. Use them for type transformations, inference, and complex type logic. Combine with infer for extracting types and recursion for deep operations. Keep types readable by breaking down complex conditions.

TypeScript Conditional Types Guide

Basic Conditional Types#

Distributive Conditional Types#

Type Inference with infer#

Practical Patterns#

Function Overloads#

Recursive Types#

Advanced Inference#

Utility Type Implementations#

Type Guards#

Practical Examples#

Best Practices#

Conclusion#

Share this article

Related articles

TypeScript Generics: Practical Patterns for Real Apps

Advanced TypeScript Generics

TypeScript Generics: A Practical Guide