typescript-best-practices.md

title	TypeScript Best Practices
inclusion	always

TypeScript Best Practices

Code Style

• Use strict TypeScript configuration (strict: true)
• Prefer const over let, avoid var
• Use meaningful variable and function names
• Use PascalCase for classes and interfaces
• Use camelCase for variables and functions
• Use UPPER_SNAKE_CASE for constants

Type Safety

• Always define return types for functions
• Use union types instead of any
• Prefer interfaces over type aliases for object shapes
• Use generic types for reusable components
• Enable noImplicitAny and strictNullChecks

Error Handling

• Use Result/Either patterns for error handling
• Prefer throwing typed errors over generic Error
• Use optional chaining (?.) and nullish coalescing (??)

Imports/Exports

• Use named exports over default exports
• Group imports: external libraries first, then internal modules
• Use absolute imports with path mapping when possible

Testing

• Write unit tests for all public functions
• Use descriptive test names
• Mock external dependencies
• Aim for high test coverage (>80%)
• Run tests with minimal verbosity to avoid session timeouts
• Use grep/filter options to run specific tests when debugging
• Prefer npm test -- --silent or yarn test --silent for automated runs