Intermediate Code District

TypeScript

JavaScript with types that catch bugs early.

TypeScript is JavaScript plus a type system that catches bugs before your code runs, and it is one of the most popular languages in web development. This track takes you from your first type annotation to the patterns real-world apps use every day: object types, unions and narrowing, generics, utility and mapped types, satisfies, and validating API data at runtime.

You already know JavaScript, so every lesson goes straight to what TypeScript adds, and the quizzes make sure you truly understand what the compiler does.

Lessons: 23
Time: 3 h
Level: Intermediate

Start the track · Why TypeScript?

Bronze open
Silver open
Gold locked

Ready to prove it?

Three exams are waiting: Bronze, Silver and Gold.

Go to the exams

What you'll be able to do

Set up a strict TypeScript project and know what tsc and Node.js each do
Describe posts, users and API responses with precise types
Model API states with discriminated unions and let the compiler check every case
Write reusable generic functions and types
Derive new types with utility, mapped and conditional types
Validate JSON from the network so your types tell the truth

The journey

1
Module 1
Why TypeScript

What types buy you, how tsc and tsconfig work, and how Node.js runs TypeScript files.

0 / 3
2
Module 2
Everyday types

Primitives, inference, arrays, tuples, literal types, and the difference between any and unknown.

0 / 4
3
Module 3
Modeling objects

Describe posts, users and API payloads with interfaces, type aliases and Record.

0 / 4
4
Module 4
Unions and narrowing

Values that can be one of several types, and how TypeScript follows your checks.

0 / 4
5
Module 5
Generics

Write one function or type that works for many types without losing safety.

0 / 3
6
Module 6
Advanced types in practice

Utility, mapped and conditional types, satisfies, as const, and validating JSON at runtime.

0 / 5