TypeScript Patterns for Backend Development

After years of "undefined is not a function" errors at 3 AM, TypeScript became non-negotiable for my backend work. Here are the patterns that work.

Why TypeScript on the Backend?

JavaScript's flexibility is its weakness in large codebases. Types give you: - Catch errors at compile time - Self-documenting code - Confident refactoring - Better IDE experience

Pattern 1: Result Types

Instead of throwing exceptions everywhere, return Result types. This makes error handling explicit and type-safe.

Pattern 2: Branded Types

Prevent mixing up IDs of different types. You can't accidentally pass a UserId where OrderId is expected.

Pattern 3: Discriminated Unions for State

Model your domain states explicitly. TypeScript will ensure you handle all cases.

Pattern 4: Strict Configuration

Enable all the strict checks in tsconfig. Yes, it's annoying at first. But these settings have caught countless bugs before production.

The Payoff

TypeScript isn't just about types. It's about building confidence in your codebase.

When I refactor now, I'm not scared. The compiler tells me exactly what broke and where. That's worth the initial learning curve.