Skip to main content

Plain JavaScript

Discouraged

Not our default choice. Use TypeScript for all new projects.

What is it​

Writing JavaScript without static type annotations, relying on runtime behavior and dynamic typing.

Why it's not our default​

  • TypeScript is the industry standard — adoption at >80% for professional projects; most libraries ship with TypeScript types.
  • No compile-time error checking — bugs that TypeScript catches at build time become runtime errors.
  • Poor IDE support compared to TS — TypeScript enables autocompletion, refactoring, inline docs, and navigation.
  • Harder to maintain at scale — lack of type contracts between modules makes refactoring risky and onboarding slow.
  • All Aliz stack tools assume TypeScript — Vite, Vitest, React, Zustand, TanStack Query all have first-class TS support.

When it makes sense​

  • Quick throwaway scripts — one-off data migrations, local utilities, or short-lived experiments where type annotation overhead outweighs the benefit.
  • Prototypes you will delete — if the code won't survive past a sprint, TypeScript setup cost may not be justified.

Alternative​

TypeScript

Migration path​

  1. Add TypeScript: npm install -D typescript and create tsconfig.json
  2. Rename files incrementally: .js → .ts, .jsx → .tsx
  3. Start with "strict": false in tsconfig, then progressively enable strict checks
  4. Use // @ts-expect-error or any temporarily for complex legacy patterns
  5. Add types for dependencies: npm install -D @types/react @types/node etc.

Resources​