TS Certificate

# TypeScript certificate - outline

## Part 1 - exam (60 min)

Topics:
- Strict mode + tsconfig options
- Types vs interfaces; unions + intersections
- Discriminated unions + narrowing
- Generics + constraints + keyof + typeof
- Utility types: Pick, Omit, Record, Partial, Required, ReturnType
- 'unknown' over 'any'; 'satisfies' operator
- Declaration files (.d.ts)
- Module resolution: NodeNext, ESM/CJS interop
- Runtime validation (Zod, Valibot) at boundaries

Passing mark: 70 percent.

## Part 2 - capstone (take-home, ~10 hours)

Ship a typed project (frontend, backend, or full-stack):

- TS strict + noUncheckedIndexedAccess + exactOptionalPropertyTypes
- Zod (or Valibot) at every input boundary
- No 'any' in your own code
- Tests with Vitest or Jest
- ESLint with @typescript-eslint
- Dockerfile + GitHub Actions CI
- Type-check step in CI (tsc --noEmit)

Submit a Git repo + README + tsconfig + a short demo.

## Grading

- Type safety + no any (30 percent)
- Validation at boundaries (20 percent)
- Modern TS usage (satisfies, narrowing) (20 percent)
- Tests + CI (15 percent)
- Code quality (15 percent)

## Tips

- noUncheckedIndexedAccess catches array out-of-bounds bugs
- exactOptionalPropertyTypes prevents silent undefined leaks
- 'as' is a code smell; reach for 'satisfies' or proper narrowing

## What this certificate proves

- You can model real-world data with types and unions
- You catch bugs at the boundary, not in production
- You ship maintainable code that survives refactors

// Finish every lesson, then visit /certificate/typescript
// to claim your certificate.
console.log('You can do it!');