Your First React App — Complete Guide
Your First React App — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of React.js Tutorial on Toolliyo Academy.
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React.js Tutorial · Lesson 3 of 100
React Architecture
Beginner → Intermediate → Advanced → Professional
Beginner · 1 — Foundations · ~12 min read · Module 1: Introduction & Setup
Introduction
This lesson is part of the beginner section. We explain React Architecture slowly, with examples you can copy and run. If something is unclear, read it twice — that is how everyone learns. React architecture is how you organize components, state, and API calls in a project. A common pattern: pages at the top, reusable components below, and separate files for API logic. Good folder structure makes code easy to find and fix. Bad structure leads to copy-paste and bugs when the team grows.
React Architecture is setup knowledge. Without it, nothing else in React will run. Spend time here until commands work without copy-paste errors.
When will you use this?
You need this before writing any React code — same as installing Word before writing a document.
- Every React job expects you to run projects locally with Node and a build tool like Vite.
- Interviewers often ask you to clone a repo and run npm install && npm run dev on day one.
Real-world: HDFC net banking folder layout
HDFC net banking has dozens of screens — accounts, transfers, cards, loans. Without folders, one App.jsx would be unmaintainable. The team splits by feature and shared UI.
Production-style code
src/
pages/
DashboardPage.jsx // /dashboard
TransferPage.jsx // /transfer
StatementsPage.jsx
features/
transfer/
TransferForm.jsx
useTransfer.js // API + validation logic
accounts/
AccountSummary.jsx
components/
Button.jsx
Modal.jsx
DataTable.jsx
api/
bankingClient.js // axios instance + interceptors
hooks/
useAuth.js
App.jsx // routes onlyWhat happens in production: A bug in the transfer form is fixed in features/transfer/ without touching the statements team files — fewer merge conflicts at scale.
Lesson example (start here)
Copy this smaller example first. Once it works, compare it with the real-world code above.
src/
pages/ → Home, Dashboard
components/ → Button, Modal
hooks/ → useAuth, useFetch
api/ → fetchUsers(), fetchOrders()Line-by-line walkthrough
| Code | What it means |
|---|---|
src/ | Part of the React Architecture example — read it together with the lines before and after. |
pages/ → Home, Dashboard | Part of the React Architecture example — read it together with the lines before and after. |
components/ → Button, Modal | Part of the React Architecture example — read it together with the lines before and after. |
hooks/ → useAuth, useFetch | Part of the React Architecture example — read it together with the lines before and after. |
api/ → fetchUsers(), fetchOrders() | Part of the React Architecture example — read it together with the lines before and after. |
How it works (big picture)
- Pages map to screens.
- Components are shared UI pieces.
- Hooks hold reusable logic.
- The api folder keeps fetch calls out of your UI code.
Do this on your computer
- Create folders: pages, components, hooks, api.
- Move shared buttons and inputs into components/.
- Put fetch calls in api/ and call them from components.
- Read the real-world section and name which part of the app uses this topic.
- Run the example locally and confirm the same behavior in the browser.
- Change one value in the example (text, initial state, or URL) and predict what will happen before you save.
Experiments — try changing this
- Change text or labels in the example and save — watch the browser update.
- Break the code on purpose (remove a bracket), read the error message, then fix it.
Remember
Split code by feature or by type (pages, components, hooks). Keep API calls separate from JSX. Start simple; refactor when files get too large.
Common questions
Do I need Redux on day one?
No. useState and props are enough for small apps.
How long should I spend on React Architecture?
Until you can explain it in your own words and run the example without looking at the answer. Beginners often need 30–60 minutes per new hook or routing topic; setup lessons may take one afternoon.
What if I get stuck on React Architecture?
Re-read the line-by-line walkthrough, check the browser console for red errors, and compare your code character-by-character with the example. Search the exact error text — someone else had it too.
Where is React Architecture used in real jobs?
See the real-world section above — the same pattern appears in LMS, banking, e-commerce, and SaaS products. Interviewers ask you to explain it using one concrete example from your project or this lesson.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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