Why TypeScript?
JavaScript's flexibility is both its greatest strength and its most common source of bugs. TypeScript adds a type system that catches entire categories of errors before code ever runs: accessing properties on null values, passing arguments in the wrong order, or misspelling object keys. These are bugs that automated tests rarely catch but that TypeScript prevents at compile time.
TypeScript also significantly improves the development experience. IDEs provide accurate autocomplete, inline documentation, and safe refactoring tools. When you rename a function parameter, every call site updates automatically. When you change an API response shape, the compiler shows you every place in the codebase that needs updating. This confidence compounds as projects grow larger.
The ecosystem has standardized on TypeScript. Major frameworks ship TypeScript definitions. Package authors write in TypeScript. Type-safe patterns are documented and expected. Working in JavaScript today means fighting against the ecosystem.
Our Approach
Every project we build starts with TypeScript in strict mode. We define data shapes with Zod schemas that serve double duty as runtime validation and compile-time types. API contracts are typed end-to-end: from database queries through server-side logic to client-side rendering, the compiler verifies data flows correctly at every boundary.
We avoid type assertions and any escapes except in genuinely unavoidable situations like third-party library gaps. Our tsconfig uses strict mode with additional checks enabled: noUncheckedIndexedAccess, exactOptionalPropertyTypes, and verbatimModuleSyntax keep our type coverage meaningful rather than superficial.
Type inference is leveraged where it provides clarity. We explicitly annotate function signatures and public APIs while letting TypeScript infer internal types.
Real-World Application: PttAVM Clone
PttAVM Clone demonstrates TypeScript's value in a complex application. The marketplace involves multiple data types (products, sellers, orders, users) flowing through various system boundaries.
Type safety examples:
- Prisma generates types from the database schema
- API routes validate inputs with Zod and infer response types
- React components receive properly typed props
- Cart state uses discriminated unions for clear state handling
When we added a new product field, TypeScript immediately identified every component that needed updating. No runtime errors, no missed cases.
When to Choose TypeScript
TypeScript belongs in any project expected to live beyond a prototype phase. The initial setup cost is minimal and the compound benefits grow with every line of code.
For quick scripts, one-off prototypes, or projects where the entire team is unfamiliar with typed languages, plain JavaScript may be faster to start with. But for any application that will be maintained by a team, grow in complexity, or handle user data where correctness matters, TypeScript pays for itself within weeks of development.
Our Track Record
We have migrated JavaScript codebases of various sizes to TypeScript, always incrementally and without breaking production. Our approach allows teams to adopt TypeScript file by file, starting with the most critical paths. We have also built greenfield TypeScript projects from scratch, establishing type patterns and conventions that keep codebases maintainable as teams and features scale.
FAQ
How strict should our TypeScript configuration be? Start with strict mode enabled. The additional strictness flags (noUncheckedIndexedAccess, exactOptionalPropertyTypes) can be added incrementally as the codebase matures. Weak TypeScript configuration provides false confidence.
How do you handle third-party libraries without types? First, check DefinitelyTyped for @types packages. For libraries without types, we write minimal type declarations in a .d.ts file. We avoid any as an escape hatch.
What about runtime type checking? TypeScript only checks types at compile time. For runtime validation of external data (API inputs, JSON parsing, user input), we use Zod. The Zod schema defines both the runtime validator and the TypeScript type.
Can you migrate our JavaScript codebase to TypeScript? Yes. We use incremental migration: rename files to .ts/.tsx, fix errors starting from leaf modules, and gradually enable stricter checks. The codebase remains deployable throughout migration.
Related Solutions
TypeScript enhances every part of our stack:
- Next.js Development - Full-stack TypeScript applications
- Node.js Development - Type-safe backend APIs
- React Development - Typed component props and state
- Prisma ORM Development - Database types from schema
- SaaS Development - Complex business logic with type safety