Angular project structure walkthrough - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Identify the purpose of the 'src/app' folder in an Angular project

In a typical Angular project, what is the main purpose of the 'src/app' folder?

A It holds the compiled JavaScript files after building the project

B It stores configuration files like angular.json and tsconfig.json

C It contains the main application code including components, services, and modules

D It contains third-party libraries and dependencies

💡 Hint

Think about where you write your Angular components and services.

The 'src/app' folder is where the main application code lives. This includes components, services, and modules that make up the Angular app.

❓ component_behavior

intermediate

What happens if you delete the 'main.ts' file?

In an Angular project, what is the effect of deleting the 'src/main.ts' file?

A The application will fail to bootstrap and will not start

B The application will run normally without any issues

C The styles will not load but the app will still start

D Only the tests will fail but the app runs fine

💡 Hint

Consider what 'main.ts' does in Angular.

'main.ts' is the entry point that bootstraps the root module. Without it, Angular cannot start the app.

📝 Syntax

advanced

Which file defines the root module in Angular?

Which file typically defines the root Angular module in a standard project structure?

A package.json

B src/main.ts

C angular.json

D src/app/app.module.ts

💡 Hint

Look for the file that declares NgModule and imports BrowserModule.

The root module is defined in 'app.module.ts' inside the 'src/app' folder.

🔧 Debug

advanced

Why does the app fail to load styles from 'src/styles.css'?

If you add styles to 'src/styles.css' but they do not apply in the app, what is the most likely cause?

A The styles file is empty so no styles are applied

B The 'angular.json' file does not include 'src/styles.css' in the styles array

C The styles are overridden by inline styles in components

D The 'package.json' is missing the styles dependency

💡 Hint

Check where global styles are registered in Angular configuration.

Global styles must be listed in the 'styles' array inside 'angular.json' to be included in the build.

❓ lifecycle

expert

Order of files executed when starting an Angular app

What is the correct order of execution for these Angular project files when the app starts?

A 4,1,2,3

B 1,2,3,4

C 4,2,1,3

D 1,4,2,3

💡 Hint

Think about what the browser loads first and how Angular bootstraps modules and components.

The browser first loads 'index.html' (4), then Angular runs 'main.ts' (1) to bootstrap the root module 'app.module.ts' (2), which loads the root component 'app.component.ts' (3).

Practice

1. Which folder in an Angular project typically contains the main application code and assets?

easy

A. src/

B. node_modules/

C. dist/

D. e2e/

Solution

1. Step 1: Understand Angular folder roles

   The src/ folder holds the source code including app files and assets.

2. Step 2: Identify other folders' purposes

   node_modules/ holds external libraries, dist/ is for build output, and e2e/ is for end-to-end tests.

3. Final Answer:

   src/ -> Option A

4. Quick Check:

   App code and assets = src/ [OK]

Hint: Remember: src means source code folder [OK]

Common Mistakes:

• Confusing node_modules with source code
• Thinking dist holds source files
• Assuming e2e contains app code

2. Which file defines the root component of an Angular application?

easy

A. app.module.ts

B. app.component.ts

C. main.ts

D. index.html

Solution

1. Step 1: Identify root component file

   The root component is defined in app.component.ts, which contains the main UI logic.

2. Step 2: Differentiate other files

   app.module.ts defines the app module, main.ts bootstraps the app, and index.html is the main HTML page.

3. Final Answer:

   app.component.ts -> Option B

4. Quick Check:

   Root component = app.component.ts [OK]

Hint: Component files end with .component.ts [OK]

Common Mistakes:

• Confusing app.module.ts with component file
• Thinking main.ts defines UI
• Assuming index.html is a component

3. Given this Angular project structure snippet:

src/
  app/
    app.module.ts
    app.component.ts
  assets/
  styles.css

Which file is responsible for declaring components and importing modules?

medium

A. assets/

B. styles.css

C. app.component.ts

D. app.module.ts

Solution

1. Step 1: Understand app.module.ts role

   This file declares components and imports other Angular modules to organize the app.

2. Step 2: Clarify other files' roles

   app.component.ts defines UI logic, styles.css holds styles, and assets/ stores static files.

3. Final Answer:

   app.module.ts -> Option D

4. Quick Check:

   Module declarations = app.module.ts [OK]

Hint: Modules declare components, components define UI [OK]

Common Mistakes:

• Mixing component and module responsibilities
• Thinking styles.css declares components
• Confusing assets folder with code files

4. You see this error when running an Angular app:
ERROR in src/app/app.module.ts: Unexpected token
What is the most likely cause in the app.module.ts file?

medium

A. Missing @NgModule decorator

B. Empty app.component.ts file

C. Syntax error like missing comma or bracket

D. Wrong file extension instead of .ts

Solution

1. Step 1: Analyze error message

   An "Unexpected token" error usually means a syntax mistake like a missing comma or bracket.

2. Step 2: Check common syntax issues in app.module.ts

   Look for missing commas, brackets, or typos in imports or declarations.

3. Final Answer:

   Syntax error like missing comma or bracket -> Option C

4. Quick Check:

   Unexpected token = syntax error [OK]

Hint: Unexpected token means syntax mistake [OK]

Common Mistakes:

• Assuming missing decorator causes token error
• Blaming wrong file extension without checking syntax
• Thinking empty component file causes this error

5. You want to add a new feature module to your Angular app. Where should you place the new module file and what must you do to use it in your app?

hard

A. Place it inside src/app/ and import it in app.module.ts

B. Place it in src/assets/ and reference it in index.html

C. Place it in src/ root and add it to main.ts

D. Place it in src/styles/ and import in styles.css

Solution

1. Step 1: Locate new module in project structure

   Feature modules go inside src/app/ to keep app code organized.

2. Step 2: Import new module in app.module.ts

   To use the new module, import it in app.module.ts so Angular knows about it.

3. Final Answer:

   Place it inside src/app/ and import it in app.module.ts -> Option A

4. Quick Check:

   Feature module location and import = Place it inside src/app/ and import it in app.module.ts [OK]

Hint: Modules live in src/app and must be imported [OK]

Common Mistakes:

• Putting modules in assets or styles folders
• Forgetting to import the module in app.module.ts
• Adding modules to main.ts or index.html incorrectly