Really understand TypeScript.
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Explicit vs Inferred
Give the variable score an explicit number type annotation.
Write actual code
No multiple choice questions. You'll write real TypeScript code in a proper editor environment.
Instant feedback
Get immediate results on your code. Fix errors and learn from mistakes in real-time.
Track progress
See your skills grow as you complete challenges across different TypeScript concepts.
Featured TypeScript categories
Start with a focused set of categories, then browse the full curriculum when you are ready.
Primitives
TypeScript builds on JavaScript by adding types, so we can describe exactly what kind of values a variable
Functions Basics
Functions are how we structure behavior. In TypeScript, you can describe parameter types and return types so
Object Types Basics
Objects model real-world entities. In TypeScript, you describe an object's shape by listing its properties
Arrays
Arrays are ordered lists of values written as T[] or Array<T>: `typescript const numbers: number[] = [1, 2,
Union & Litteral Types
Union types let a value be one of several possibilities, while literal types restrict values to exact
Type Aliases
Type aliases give a name to any type so you can reuse it throughout your code: `typescript type UserId =
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David Shore
Creator of Codington
"I built this because I teach TypeScript regularly. I needed a way for students to practice the syntax mechanics repeatedly until it clicked, without getting stuck on VS Code configuration."