TypeScript Refactor Best Practices

Comprehensive TypeScript refactoring and modernization guide designed for AI agents and LLMs. Contains 43 rules across 8 categories, prioritized by impact to guide automated refactoring, code review, and code generation.

When to Apply

Reference these guidelines when:

• Refactoring TypeScript code for type safety and maintainability
• Designing type architectures (discriminated unions, branded types, generics)
• Narrowing types to eliminate unsafe as casts
• Adopting modern TypeScript 4.x-5.x features (satisfies, using, const type parameters)
• Optimizing compiler performance in large codebases
• Implementing type-safe error handling patterns
• Reviewing code for TypeScript quirks and pitfalls

Rule Categories by Priority

| Priority | Category | Impact | Prefix |