TypeScript

Why this stage matters

Almost every serious frontend job lists TypeScript, and Angular is built on it. It catches whole classes of bugs before the browser does, and it makes AI coding tools far more accurate because they can read your types.

What to learn

1. Must know

   Types, Interfaces & Narrowing

   Mark as done

   Primitive and object types, unions, literal types, type guards, and discriminated unions for UI state.

   You're done when

   • You model loading/success/error state as a discriminated union instead of three booleans.
   • You never reach for 'any' to silence an error.

   Resources

   • Learn TypeScript 2022Elzero Web School · Course · Arabic
   • TypeScript HandbookDocs
2. Must know

   Generics & Utility Types

   Mark as done

   Writing reusable typed functions and components, and using Partial, Pick, Omit, Record, and ReturnType.

   You're done when

   • You can write a typed generic fetch helper or list component.
   • You derive types from other types instead of duplicating them.

   Resources

   • Type ChallengesPractice
   • Total TypeScript — free tutorialsCourse
3. Learn next

   Runtime Validation (Zod, Valibot)

   Mark as done

   TypeScript disappears at runtime. Validate API responses and form input at the boundary and infer types from the schema.

   You're done when

   • API data entering your app is parsed with a schema, not cast with 'as'.

   Resources

   • Zod docsDocs
   • Valibot docsDocs

Common mistakes

• Writing types for the compiler instead of for the reader. Good types document intent.
• Going deep into type gymnastics too early. Learn the 20% you use daily first.