Course catalog
Add types to your JavaScript and catch bugs before they ship.
TypeScript is the default professional dialect of JavaScript — the language most jobs and most AI-generated code now assume. This course adds types to the JavaScript you already know: annotations and inference, interfaces, optional and readonly fields, union and literal types, then functions, generics, and narrowing. You'll learn to read the type errors the compiler gives you, choose unknown over any, type the JSON your APIs return, and migrate a plain .js file to .ts incrementally. Typed code is also easier for agents to write and for you to review — so this compounds with everything else.
Section 1
Annotations, inference, and the basic types.
Section 2
Describe object shapes and either/or types.
Ship a secure TypeScript app built with AI in your workflow: tested algorithms, tools kept inside safe limits, architecture choices you can explain, and releases you can check after they go out.
16 course sequence
Build and share a tested full-stack React app: a screen everyone can use, data only its owner can see, APIs with clear limits, realtime updates that stay correct, and deploys you can roll back.
14 course sequence
Eligible first-time members can get 7 free days · Cancel anytime
Get startedSection 3
Type functions, reuse with generics, narrow unions.
Section 4
Errors, any vs unknown, API data, migration.