Welcome
 |  |
Step-by-Step Introduction to the [React] Web Framework
created by Anthropic’s AI Claude at the request of Serge Tahé - September 2026
This document is a translation of the original French version, generated using an automated tool. Some expressions or technical terms may not fully reflect the original meaning.
This course shows, step by step, how to write a web application with the React 19 library: a single-page application (SPA) whose pages are built in the browser from the JSON data of a server.
It starts with 25 small examples, each focused on a single concept: a Vite project, function components and JSX, state (useState, useReducer), events, controlled fields, validation and React Hook Form; props, children, the life cycle (useEffect), contexts and custom hooks; routing with React Router, lazy loading and guards; asynchronous code and shared state (use() and Suspense, Zustand, localStorage); internationalization with i18next; and finally talking to the server (fetch, Vite proxy, httpOnly cookie, useActionState, TanStack Query, server errors attached to form fields).
The server is treated as a black box: it is the JSON server of the RdvMedecins application, written with NestJS. You install it, study its API and query it with 48 curl examples, without having to read its code.
Then comes a complete case study: the React client of RdvMedecins, an appointment-booking application for a medical practice, in which every file is commented, followed by its deployment.
This course follows the NestJS course, in which the server builds the pages, and uses the same outline as the Vue.js and Angular courses. The same screens are also written for a phone with Flutter. The course A React/NestJS Client/Server Example studies both the server and the client.