React Kickoff: Concepts & Setup
What is React, why declarative UI matters, how diffing works; quick setup with a dev server; folder layout; and first render with createRoot.
React Kickoff: Concepts & Setup is a free React Academy lesson on CoddyKit — lesson 1 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the React Academy learning path, one of 3 lessons in the course, and your progress syncs across the web and the CoddyKit app.
What is React?
React is a UI library for building apps from small, reusable components.
- Think in components.
- Describe UI for a state (declarative).
- React handles efficient updates.
Declarative mindset
Declarative code describes the result; React computes DOM changes for you. Imperative code micromanages each update.
Diffing in plain words
React builds a lightweight virtual DOM and diffs it with the previous tree to apply minimal, focused DOM updates.
Project setup
Setup:
- Create app (e.g., npm create vite@latest).
- Install deps (npm install).
- Run dev server (npm run dev).
Folder layout
Folder basics:
- index.html contains
div#root. - src/main.jsx bootstraps
createRoot. - src/App.jsx defines your first component.
Your first component
First render: mount a root and render App(); click to see state-driven updates.
<div id="root"></div>
Declarative UI check
Quick check: What is the key idea behind React's declarative UI?
Recap
Recap: Components + declarative rendering + diffing. Set up a dev server and render App() with createRoot.
Frequently asked questions
Is the “React Kickoff: Concepts & Setup” lesson free?
Yes — the full text of “React Kickoff: Concepts & Setup” is free to read here on the web, and the React Academy course includes 3 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the React Academy course, upgrade to CoddyKit PRO.
What will I learn in “React Kickoff: Concepts & Setup”?
What is React, why declarative UI matters, how diffing works; quick setup with a dev server; folder layout; and first render with createRoot. You practise React Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start React Academy?
No prior experience is required. React Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 3, so you can start here or from the beginning and move at your own pace.
How long does the “React Kickoff: Concepts & Setup” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this React Academy lesson?
Yes. Every React Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- React Kickoff: Concepts & Setup
- Project Setup: Vite, Layout & Dev Server
- First Component & Render