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Master TypeScript’s type system through practice

High-quality types can help improve projects’ maintainability while avoiding potential bugs. Type Challenges is a collection of challenges aimed at helping you better understand how the TypeScript type system works, writing your own utilities, or just having fun with the challenges.

Progressive difficulty

Start with warm-up challenges and progress through easy, medium, hard, and extreme levels

Learn by doing

Practice writing type utilities that you can use in real-world projects

Active community

Join developers solving real-world type problems and sharing solutions

Multiple environments

Solve challenges in TypeScript Playground, VS Code, or your local IDE

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Why Type Challenges?

TypeScript’s type system is Turing complete, which means you can express incredibly complex type transformations. But understanding how to leverage this power takes practice. This project helps you:
  • Understand the type system deeply - Go beyond basic type annotations
  • Write your own utilities - Build reusable type helpers for your projects
  • Avoid potential bugs - Catch errors at compile time with precise types
  • Join a learning community - Ask questions and share solutions with others

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Challenge categories

Warm-up

Get started with the basics - perfect for your first challenge

Easy

13 challenges covering fundamental type operations like Pick, Readonly, and Tuple operations

Medium

Advanced type manipulations including string operations and recursive types

Hard

Complex type challenges requiring deep understanding of TypeScript’s type system
All challenges work in TypeScript’s strict mode.

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How it works

In Type Challenges, we use the type system itself to do assertions. You’ll write type definitions that must pass type-level tests. Here’s a simple example from the “Hello World” challenge: 
// Your task: change this to make the tests pass
type HelloWorld = any // expected to be a string

// Test cases (these must pass)
type cases = [
  Expect<NotAny<HelloWorld>>,
  Expect<Equal<HelloWorld, string>>,
]
The solution is to replace any with string: 
type HelloWorld = string // ✅ Tests pass!

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Getting started

Quick start

Jump right in with your first challenge

Play locally

Set up challenges in your IDE

TypeScript Playground

Try in browser (no setup needed)

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Community and resources

  • Discord - Join the Type Challenges Discord to discuss challenges
  • VS Code Extension - Install the Type Challenges extension
  • Share solutions - Contribute your solutions and learn from others
  • Propose challenges - Have a real-world type problem? It might become a challenge!
Stuck on a challenge? Don’t worry! The community is here to help. Many challenges have solution discussions where you can learn different approaches.

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