Project structure overview in React - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding React project folder roles

In a typical React project, which folder usually contains reusable UI components like buttons and headers?

A public

B src/components

C node_modules

D src/assets

💡 Hint

Think about where you keep pieces you use many times in your app.

The src/components folder holds reusable UI parts like buttons and headers. The public folder is for static files, node_modules stores installed packages, and src/assets holds images or styles.

❓ component_behavior

intermediate

Effect of placing files in public folder

What happens if you put an image file inside the public folder and reference it in your React app?

A The image will cause a build error.

B The image is bundled and optimized by React automatically.

C The image cannot be accessed by the app at all.

D The image is served as a static file and can be accessed via a URL path.

💡 Hint

Think about how static files are handled in web projects.

Files in the public folder are served directly as static assets. They are not processed by React but can be accessed via URL paths.

📝 Syntax

advanced

Correct import path for a component

Given a React project with this structure:

src/
  components/
    Button.jsx
  App.jsx

Which import statement correctly imports Button into App.jsx?

A import Button from './components/Button';

B import Button from '../components/Button';

C import Button from './Button';

D import Button from 'components/Button';

💡 Hint

Consider the relative path from App.jsx to Button.jsx.

Since App.jsx and components are both inside src, the correct relative path is ./components/Button.

🔧 Debug

advanced

Why does this React app fail to find a CSS file?

A developer places styles.css inside src/assets but imports it in App.jsx as:

import '../assets/styles.css';

Why does this cause an error?

A The file extension must be .module.css to import CSS.

B CSS files cannot be imported in React components.

C The import path is incorrect because <code>App.jsx</code> is inside <code>src</code>, so '../assets' goes outside <code>src</code> which doesn't exist.

D The assets folder must be inside public to import CSS.

💡 Hint

Check the relative path carefully from App.jsx location.

Since App.jsx is inside src, using ../assets tries to go outside src, which is invalid. The correct path is ./assets/styles.css.

❓ state_output

expert

Effect of moving stateful logic to a separate folder

In a React project, a developer moves all custom hooks managing state from src/components to src/hooks. What is the main benefit of this change?

A It improves code organization by separating UI components from state logic, making the project easier to maintain.

B It automatically optimizes the app performance by React.

C It prevents components from re-rendering unnecessarily.

D It causes the app to break because hooks must be inside components.

💡 Hint

Think about how separating concerns helps in bigger projects.

Moving custom hooks to a dedicated src/hooks folder helps keep UI components focused on display, while hooks handle state logic. This separation makes the code cleaner and easier to maintain.

Practice

1. Which folder in a React project usually contains reusable UI pieces like buttons or headers?

easy

A. pages/

B. components/

C. styles/

D. public/

Solution

1. Step 1: Understand folder purposes

   The components/ folder holds reusable UI parts like buttons or headers.

2. Step 2: Compare with other folders

   public/ holds static files, styles/ holds CSS, and pages/ holds full page components.

3. Final Answer:

   components/ -> Option B

4. Quick Check:

   Reusable UI pieces = components/ [OK]

Hint: Reusable UI parts go in components/ folder [OK]

Common Mistakes:

• Confusing public/ with components/
• Putting styles in components/
• Using pages/ for small UI parts

2. Which file is typically found inside the public/ folder in a React project?

easy

A. index.html

B. Button.jsx

C. App.js

D. styles.css

Solution

1. Step 1: Identify public folder role

   The public/ folder holds static files served directly, like index.html.

2. Step 2: Match files to folders

   App.js and Button.jsx are source code files, styles.css is usually in styles/.

3. Final Answer:

   index.html -> Option A

4. Quick Check:

   Static files like index.html = public/ [OK]

Hint: index.html is always in public/ folder [OK]

Common Mistakes:

• Putting App.js in public/
• Confusing styles.css location
• Thinking Button.jsx is static file

3. Given this React project structure inside src/:

src/
  components/
    Header.jsx
  pages/
    Home.jsx
  styles/
    main.css

Where should you import Header to use it on the home page?

medium

A. import Header from '../components/Header';

B. import Header from './components/Header';

C. import Header from '../pages/Header';

D. import Header from './Header';

Solution

1. Step 1: Locate Home.jsx and Header.jsx relative paths

   Home.jsx is inside pages/, Header.jsx is inside components/ at the same src level.

2. Step 2: Determine correct import path

   From pages/Home.jsx, since pages/ and components/ are sibling folders under src/, go up one level with '..' to src/ then into components/: '../components/Header'.

3. Step 3: Check options carefully

   import Header from './components/Header'; uses './components/Header' which assumes components inside pages/, which is incorrect. import Header from '../components/Header'; uses '../components/Header' which is correct.

4. Final Answer:

   import Header from '../components/Header'; -> Option A

5. Quick Check:

   Relative import from pages to components = ../components/Header [OK]

Hint: Use ../ to go up one folder from pages to src [OK]

Common Mistakes:

• Using ./components from pages/
• Importing from pages/ folder
• Forgetting relative path syntax

4. You see this import in a React file:
import styles from './styles.css';
But the styles folder is inside src/, at the same level as components/, and the file is inside src/components/. What is wrong?

medium

A. The import should be './styles/styles.css' instead

B. You cannot import CSS files in React

C. The import path should be '../styles/styles.css' to go up one folder

D. The styles folder should be inside components/

Solution

1. Step 1: Understand folder locations

   The file is in src/components/, styles folder is in src/. To import styles.css inside styles/, you must go up one level from components/.

2. Step 2: Fix import path

   Using './styles.css' looks for styles.css inside components/, which is wrong. The correct path is '../styles/styles.css'.

3. Step 3: Check options

   The import path should be '../styles/styles.css' to go up one folder correctly identifies the need to go up one folder into the styles folder. You cannot import CSS files in React is false (CSS can be imported). The import should be './styles/styles.css' instead looks inside components/. The styles folder should be inside components/ suggests wrong folder placement.

4. Final Answer:

   The import path should be '../styles/styles.css' to go up one folder -> Option C

5. Quick Check:

   Go up one folder to access styles folder [OK]

Hint: Use ../ to go up from components to src for styles [OK]

Common Mistakes:

• Using ./ without going up folder
• Thinking CSS can't be imported
• Wrong folder nesting assumptions

5. You want to organize a React project with these goals:
- Keep reusable UI parts separate
- Have full pages grouped
- Store CSS files in one place
- Serve static files like images and index.html

Which folder structure best fits these goals inside src/ and public/?

hard

A. src/ui/, src/screens/, src/css/, public/assets/

B. src/, public/components/, public/pages/, public/styles/

C. src/components/, src/pages/, public/styles/, public/

D. src/components/, src/pages/, src/styles/, public/

Solution

1. Step 1: Match goals to folder roles

   Reusable UI parts go in components/, full pages in pages/, CSS in styles/, static files like images and index.html in public/.

2. Step 2: Evaluate options

   src/components/, src/pages/, src/styles/, public/ matches exactly: src/components/, src/pages/, src/styles/, public/. src/ui/, src/screens/, src/css/, public/assets/ uses non-standard folder names and puts static files in public/assets/ only. src/components/, src/pages/, public/styles/, public/ puts styles in public/, which is not typical. src/, public/components/, public/pages/, public/styles/ puts components and pages in public/, which is incorrect.

3. Final Answer:

   src/components/, src/pages/, src/styles/, public/ -> Option D

4. Quick Check:

   Standard React folders = components, pages, styles, public [OK]

Hint: Use components, pages, styles in src and public for static files [OK]

Common Mistakes:

• Putting CSS in public/
• Using non-standard folder names
• Mixing src and public roles