TypeScript Best Practices for Large Codebases

Working on enterprise applications at 3PTrades has taught me valuable lessons about using TypeScript effectively in large codebases. Here are the practices that have made the biggest difference.

1. Strict Type Checking

Always enable strict mode in your tsconfig.json. This catches potential bugs early and ensures type safety throughout your codebase.

2. Use Type Inference Wisely

Let TypeScript infer types when possible. Explicit types should only be added when they provide value or clarity.

3. Leverage Utility Types

TypeScript's built-in utility types like Pick, Partial, Readonly, and Omit are powerful tools for creating derived types without duplication.

4. Generic Constraints

Use generic constraints for flexible, type-safe functions that work with multiple types while maintaining type safety.

5. Discriminated Unions

Use discriminated unions for type-safe state management. This pattern is especially useful for handling loading, success, and error states.

6. Avoid any

Use unknown instead of any when you don't know the type. This forces you to perform type checking before using the value.

7. Type Guards

Create custom type guards for complex type checking. This makes your code more readable and type-safe.

Conclusion

These practices have significantly improved code quality and maintainability in our large codebase. TypeScript's type system is powerful when used correctly, and these patterns help leverage that power effectively.