TYPESCRIPT · FROM FIRST TYPES TO WORKING APPLICATIONS
A complete practical learning path through types, functions, generics, modules, browser code and runtime validation. Finish with a tested task manager that saves your work.
Know variables, loops, functions, arrays and objects. Use Node.js 22 or 24, npm and a code editor. The setup lesson works on macOS, Windows and Linux.
Every checkpoint pins TypeScript 5.9.3 and enables strict checking. You do not need a frontend framework or a global compiler installation.
Read the explanation, trace the source, predict the result and run the example. Each lesson includes complete files, expected output and an independent exercise with an explained answer.
Extract each ZIP into a separate folder. Run npm install, npm run check and npm run build before following that lesson’s run instructions.
Download all 24 checkpoints with offline explanations, or try the finished browser task manager before building it yourself.
The demo saves tasks only in this browser. It requires no account and does not sync across devices.
COURSE MODULE
Understand the path from TypeScript source to running JavaScript.
Choose useful annotations while letting the compiler infer obvious values.
Model a sequence, a fixed-position record, and a read-only view.
Describe inputs, defaults, rest parameters and related call signatures.
COURSE MODULE
Define reusable object contracts and understand structural compatibility.
Represent valid alternatives and handle every state.
Use runtime evidence to refine uncertain types.
Handle missing data without disabling the checker.
COURSE MODULE
Preserve relationships between input and output types.
Derive property names and values from existing contracts.
Create focused input, output and lookup types without copying fields.
Build small type transformations and understand their limits.
Keep precise values while checking a configuration contract.
COURSE MODULE
Split responsibilities across files with explicit imports.
Model stateful behavior and inject dependencies through a contract.
Model asynchronous work and handle expected failures explicitly.
Turn unknown JSON into trusted application data.
Connect typed JavaScript to a working browser form.
COURSE MODULE
Verify compile-time contracts and business behavior separately.
Understand strict checks, output settings and source maps.
Introduce checking incrementally while understanding declaration files.
COURSE MODULE
Build reusable task behavior before connecting it to a screen.
Combine typed models, DOM events, validation and local storage.
Prepare the browser project for static hosting and review the complete learning path.
Learn how static checks catch mistakes and why API responses, saved data and user input still need runtime validation. Practice both compiler checks and executable behavior tests.
Finish by building and publishing the browser project. The final lesson includes a release checklist and further study paths for framework typing, declarations, project references and decorators.
Official TypeScript handbook ↗