Skip to main content

​
Type Challenges Overview

Type Challenges is a collection of TypeScript type exercises designed to help you master the TypeScript type system. Each challenge focuses on different aspects of type manipulation, from basic utility types to advanced type-level programming.

​
How It Works

Type Challenges uses TypeScript’s type system itself to validate your solutions. Instead of writing runtime code, you’ll implement type utilities that satisfy test cases at compile time.

​
Challenge Structure

Each challenge includes:
  • Problem Description: What you need to implement
  • Starting Template: Basic type definition to complete
  • Test Cases: Type assertions that must pass
  • Examples: Usage examples showing expected behavior

​
Example Challenge

Here’s what a typical challenge looks like: 
// Your implementation
type MyPick<T, K> = any // Replace 'any' with your solution

// Test cases (must have no type errors)
type test = Expect<Equal<MyPick<Todo, 'title'>, { title: string }>>

​
Difficulty Levels

Challenges are organized into five difficulty tiers:

Warm-up

1 challenge - Get started with the basics

Easy

13 challenges - Learn fundamental type operations

Medium

104 challenges - Build intermediate skills

Hard

55 challenges - Master advanced concepts

Extreme

17 challenges - Push the limits of the type system

​
Getting Started

1

Start with Warm-up

Begin with the Hello World challenge to understand the format
2

Progress through Easy

Work through Easy challenges to build foundational knowledge
3

Advance gradually

Move to Medium and Hard as you gain confidence
4

Challenge yourself

Tackle Extreme challenges when you’re ready for the ultimate test

​
Learning Path

​
Core Concepts You’ll Learn

  • Mapped Types: Transform existing types into new ones
  • Conditional Types: Create types based on conditions
  • Template Literal Types: Manipulate string types
  • Recursive Types: Build complex types through recursion
  • Union & Intersection: Combine and intersect types
  • Type Inference: Extract and infer types from existing structures

​
Tips for Success

Understanding TypeScript’s type system fundamentals is essential. Review sections on:
  • Generics
  • Conditional Types
  • Mapped Types
  • Template Literal Types
Don’t skip difficulty levels. Each tier builds on concepts from previous ones. Master the basics before advancing.
Test your solutions in the TypeScript Playground to see how types behave and check for errors.
After solving a challenge (or getting stuck), review community solutions to learn different approaches and best practices.
Remember you’re working at compile-time, not runtime. Focus on type transformations rather than value operations.

​
Common Patterns

As you progress, you’ll encounter these recurring patterns:

​
Pattern Matching with Conditional Types

type IsString<T> = T extends string ? true : false

​
Mapping Over Object Keys

type Readonly<T> = {
  readonly [K in keyof T]: T[K]
}

​
Type Inference with infer

type ReturnType<T> = T extends (...args: any[]) => infer R ? R : never

​
Recursive Type Processing

type DeepReadonly<T> = {
  readonly [K in keyof T]: DeepReadonly<T[K]>
}

​
Resources

TypeScript Playground

Test your type solutions interactively

TypeScript Handbook

Official TypeScript documentation

Type Challenges Repository

Original challenge repository and community solutions

Utility Types Reference

Built-in TypeScript utility types

​
Next Steps

Ready to begin? Start with the Warm-up challenge or jump directly to: