Foundations & Mental Model
Why TypeScript, types as sets of values, structural typing, and how inference really works. Start →
TypeScript Deep Dive
A standalone, intermediate→advanced course on TypeScript's type system, written for TypeScript 7 (the native compiler) and the 6.0 defaults. From structural typing and inference to generics, conditional & mapped types, template literals, recursive types, decorators, the compiler, and typing real APIs — every topic taught through annotated code that shows exactly what the compiler infers.
What you’ll learn
Section titled “What you’ll learn”Everyday Types, Deep
Literals & widening, unions & intersections, objects/arrays/tuples, functions, and narrowing. Sharpen →
Generics
Type parameters, constraints, conditional types, and how inference and infer work. Generalize →
Type-Level Programming
Mapped types, template literal types, keyof & indexed access, the utility types, and recursion. Compute →
Classes & Advanced OOP
Fields & access, this types, stage-3 decorators, and mixins. Model →
The Compiler & Tooling
The TypeScript 6/7 defaults, the native compiler, module resolution, declaration files, and emit. Configure →
Practical Mastery
Typing APIs & boundaries, nullability & never, performance pitfalls, and migration strategy. Apply →
How the Checker Thinks
Assignability, inference, and control-flow analysis as real algorithms — plus erasure/emit and the checker’s performance model. Go deeper →
Reading & Reviewing TypeScript
A 24-pattern AI bug catalog, a review checklist, verification tools, and four worked reviews of real-looking code. Review →
How this course works
Section titled “How this course works”Types as the star
This is a course about the type system, not JavaScript syntax. Examples are annotated to show exactly what the compiler infers and where it errors — the way you actually read TypeScript.
Mental models first
Every topic starts from a model — types as sets of values, structural compatibility, inference sites — so advanced features stop feeling like magic and start feeling inevitable.
Depth, not just usage
Not “here’s Partial<T>” but “here’s how Partial is built, and how to build your own.” You’ll read and write type-level code with confidence.
Diagrams that explain
Type widening, narrowing flow, conditional-type distribution, and module resolution as theme-aware Mermaid diagrams. Current as of TypeScript 7.0 (July 2026), with older behaviour labelled. Bilingual (English / ไทย) with saved quiz progress.