TypeScript Course

TypeScript is JavaScript with a type system bolted on top — every valid JavaScript file is already valid TypeScript, but TypeScript lets you describe the shapes of your data and catches a huge class of mistakes before your code ever runs, right in your editor. This course takes you from a plain .ts file through interfaces, generics, and the compiler configuration that ties it all together.

What you'll learn

The first half covers TypeScript's type system on its own terms: basic types, interfaces for describing object shapes, typed functions, and classes with access modifiers. The second half moves into the features that make TypeScript genuinely powerful rather than just "JavaScript with type annotations" — enums and tuples, generics for reusable typed code, union and intersection types, narrowing a union down to a specific case, the built-in utility types that reshape existing types, and modules for splitting code across files.

Every lesson shows real TypeScript code next to what actually happens — either the JavaScript output after compiling, or the exact compiler error tsc produces when a lesson is specifically about catching a mistake. This course assumes you're already comfortable with JavaScript fundamentals; if you're not, the JavaScript course is the place to start first.

Lessons

  1. Introduction
  2. Basic Types
  3. Interfaces
  4. Functions
  5. Classes
  6. Enums & Tuples
  7. Generics
  8. Union & Intersection Types
  9. Type Narrowing
  10. Utility Types
  11. Modules
  12. Compiling with tsconfig
Where to start: begin with Introduction and go in order — generics, union types, and narrowing (lessons 07 through 09) each lean on the interfaces and functions covered earlier, so skipping ahead tends to mean backtracking.