Project structure overview in NextJS - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is the purpose of the app directory in Next.js 14?

In Next.js 14, what is the main role of the app directory in a project?

A It holds configuration files like <code>next.config.js</code> and environment variables.

B It contains server components and routes that define the app's UI and navigation.

C It stores static assets like images and fonts for the project.

D It is used only for API routes and backend logic.

💡 Hint

Think about where you define pages and layouts in Next.js 14.

The app directory is where you create server components and define routes using folders and files. It controls the UI structure and navigation.

❓ component_behavior

intermediate

What happens if you place a page file outside the app directory?

In a Next.js 14 project, what will happen if you create a page file like page.tsx outside the app directory?

A The page will not be recognized and will not be part of the routing system.

B The page will work normally and be accessible via URL.

C Next.js will throw a build error preventing the app from running.

D The page will be treated as an API route.

💡 Hint

Where does Next.js expect page files in the new app router?

Next.js 14 expects page files inside the app directory. Files outside are ignored for routing.

📝 Syntax

advanced

Identify the correct file to define a layout for all pages in Next.js 14

Which file should you create inside the app directory to define a layout that wraps all pages in your Next.js 14 app?

A <code>page.tsx</code>

B <code>app.tsx</code>

C <code>layout.tsx</code>

D <code>root.tsx</code>

💡 Hint

Layouts wrap pages and share UI like headers or footers.

The layout.tsx file inside the app directory defines a layout component that wraps all nested pages and components.

🔧 Debug

advanced

Why does this Next.js 14 project fail to load the homepage?

Given this project structure: - app/ - layout.tsx - home.tsx Why does the homepage not load at the root URL?

A Because the homepage file must be named <code>page.tsx</code>, not <code>home.tsx</code>.

B Because <code>layout.tsx</code> is missing a default export.

C Because the <code>app</code> directory must be named <code>pages</code>.

D Because the <code>home.tsx</code> file must be inside a folder named <code>home</code>.

💡 Hint

Next.js uses specific file names for routing.

Next.js 14 requires the homepage file to be named page.tsx inside the app directory to serve it at the root URL.

❓ lifecycle

expert

How does Next.js 14 handle server and client components in the app directory?

In Next.js 14, how does the framework decide which components in the app directory run on the server versus the client?

A Next.js runs all components on both server and client automatically without distinction.

B All components run on the client unless wrapped in a special <code>ServerComponent</code> tag.

C Components run on the server or client based on their file extension: <code>.server.tsx</code> or <code>.client.tsx</code>.

D By default, components are server components unless marked with <code>'use client'</code> at the top to run on the client.

💡 Hint

Look for a special directive string at the top of files.

Next.js 14 treats components as server components by default. Adding 'use client' at the top marks them as client components.

Practice

1. What is the main purpose of the app/ folder in a Next.js project?

easy

A. To organize pages, layouts, and API routes

B. To store static files like images and fonts

C. To hold configuration files like next.config.js

D. To keep test files and mocks

Solution

1. Step 1: Understand the role of app/ folder

   The app/ folder is designed to organize the main parts of the app such as pages, layouts, and API routes.

2. Step 2: Compare with other folders

   The public/ folder holds static files, and config files are outside app/. So, app/ is for app structure.

3. Final Answer:

   To organize pages, layouts, and API routes -> Option A

4. Quick Check:

   app/ folder = organize pages/layouts/API [OK]

Hint: Remember: app/ is your app's main structure folder [OK]

Common Mistakes:

• Confusing app/ with public/
• Thinking config files go inside app/
• Assuming app/ holds only pages, ignoring layouts and APIs

2. Which folder should you place an image file in a Next.js project to serve it statically?

easy

A. app/

B. api/

C. components/

D. public/

Solution

1. Step 1: Identify static file storage

   Static files like images should be placed in the public/ folder so they can be served directly.

2. Step 2: Exclude other folders

   app/ is for pages/layouts, components/ is for React components, and api/ is for backend routes, so none are for static files.

3. Final Answer:

   public/ -> Option D

4. Quick Check:

   Static files = public/ folder [OK]

Hint: Static files go in public/ folder, not app/ [OK]

Common Mistakes:

• Putting images inside app/ folder
• Confusing components/ with static file storage
• Trying to serve images from api/ folder

3. Given this Next.js project structure:

app/
  layout.js
  page.js
public/
  logo.png

Which statement is true about accessing logo.png in the browser?

medium

A. You can access it at /logo.png

B. You must import it in page.js to use it

C. It is not accessible because it's inside public/

D. You can access it at /app/logo.png

Solution

1. Step 1: Understand public/ folder behavior

   Files in public/ are served at the root URL path, so logo.png is accessible at /logo.png.

2. Step 2: Check other options

   Importing is optional for static files; app/ folder files are not served as static assets, so /app/logo.png is invalid.

3. Final Answer:

   You can access it at /logo.png -> Option A

4. Quick Check:

   public/ files = root URL access [OK]

Hint: Static files in public/ map to root URL path [OK]

Common Mistakes:

• Thinking you must import static files to access them
• Trying to access static files via /app/ path
• Assuming public/ files are not accessible

4. You see this error in your Next.js app: "Module not found: Can't resolve './logo.png'". Your project has logo.png inside public/. What is the likely cause?

medium

A. You placed logo.png inside app/ instead of public/

B. You tried to import logo.png from public/ using a relative path

C. The logo.png file is missing from public/

D. Next.js does not support PNG images

Solution

1. Step 1: Understand how to use files in public/

   Files in public/ are accessed via URL paths, not imported with relative paths in code.

2. Step 2: Identify the error cause

   Trying to import logo.png with a relative path causes "Module not found" error because public/ files are not part of the module system.

3. Final Answer:

   You tried to import logo.png from public/ using a relative path -> Option B

4. Quick Check:

   Importing public/ files = error [OK]

Hint: Don't import public/ files; use URL paths instead [OK]

Common Mistakes:

• Importing static files from public/ folder
• Assuming public/ files are part of module imports
• Thinking Next.js can't serve PNG images

5. You want to create a new page with a custom layout in your Next.js app. Where should you place the layout and page files to follow the recommended project structure?

hard

A. Place both files inside components/ folder

B. Put layout.js in public/ and page.js in app/

C. Place both layout.js and page.js inside a new folder under app/

D. Put page.js in app/ and layout.js in api/

Solution

1. Step 1: Recall Next.js app folder structure

   In Next.js, pages and their layouts are organized inside folders under app/ to group related files.

2. Step 2: Exclude incorrect placements

   public/ is for static files, components/ is for reusable UI parts, and api/ is for backend routes, so these are not correct for layouts/pages.

3. Final Answer:

   Place both layout.js and page.js inside a new folder under app/ -> Option C

4. Quick Check:

   Layouts and pages live together under app/ [OK]

Hint: Keep layouts and pages together inside app/ folders [OK]

Common Mistakes:

• Putting layouts in public/ or api/
• Separating layout and page files into unrelated folders
• Confusing components/ with page structure