TypeScript — Free Quiz Course

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Test your TypeScript knowledge: type annotations and inference, interfaces vs types, unions, generics, narrowing, and the compiler.

5 chapters, 50 questions. Free, no signup. Progress is saved in your browser.

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  1. Chapter 1: Types & Inference
    Type annotations, what the compiler infers on its own, primitives, arrays and tuples, and the special types: any, unknown, void, and never.
  2. Chapter 2: Interfaces, Types & Unions
    Interface vs type alias, optional and readonly properties, union and intersection types, and literal types.
  3. Chapter 3: Functions & Generics
    Typing parameters and return values, optional and default parameters, typing destructured objects, and writing your first generics.
  4. Chapter 4: Narrowing & Type Guards
    How TypeScript narrows types with typeof, instanceof and in, discriminated unions, type predicates, and when (not) to use as.
  5. Chapter 5: The Compiler & Ecosystem
    tsconfig and strict mode, what gets erased at runtime, declaration files, and validating runtime data with tools like Zod.

Course completed

You finished every chapter — best score/.

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How it works

Each chapter is a short quiz: one question at a time, with immediate feedback and an explanation after every answer. Wrong answers teach you as much as right ones.

Your progress is stored in your browser (localStorage), so you can leave and come back any time. Nothing leaves your machine, and there is no account or signup.

The questions are based on tutorials published on this site — every chapter links the related posts, and you can grab the free TypeScript Handbook to study the whole topic.