Top 25 Angular basic interview questions and answers for freshers 2025

Angular is a popular framework, and freshers often face questions about its core concepts during interviews. Below is a list of Top 25 Angular Interview Questions with Answers tailored for freshers. These questions are designed to be easy to understand and explain in an interview setting.

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1. What is Angular?

Answer:
Angular is a TypeScript-based open-source front-end web application framework developed by Google. It is used to build dynamic, single-page applications (SPAs) and provides features like two-way data binding, dependency injection, and modular development.

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2. What are the key features of Angular?

Answer:

• Two-way data binding: Syncs data between the model and view.
• Dependency Injection: Helps in creating and injecting dependencies.
• Modularity: Organizes code into modules.
• Directives: Extends HTML with custom attributes.
• TypeScript: Provides better tooling and error detection.
• Routing: Enables navigation between views.

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3. What is TypeScript?

Answer:
TypeScript is a superset of JavaScript that adds static typing and other features like interfaces, classes, and decorators. Angular is built with TypeScript, which helps in catching errors during development.

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4. What is a module in Angular?

Answer:
A module is a container for a group of related components, directives, pipes, and services. It is defined using the @NgModule decorator. Every Angular app has at least one module, called the root module (AppModule).

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5. What is a component in Angular?

Answer:
A component is a building block of an Angular application. It consists of:

• A TypeScript class (for logic).
• An HTML template (for view).
• A CSS file (for styling).

Components are defined using the @Component decorator.

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6. What is data binding in Angular?

Answer:
Data binding is a mechanism to sync data between the component and the view. Angular supports:

• Interpolation: {{ data }}
• Property binding: [property]="data"
• Event binding: (event)="method()"
• Two-way binding: [(ngModel)]="data"

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7. What is the difference between AngularJS and Angular?

Answer:

• AngularJS is based on JavaScript and uses controllers and $scope.
• Angular (2+) is based on TypeScript and uses components and modules.

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8. What is a directive in Angular?

Answer:
Directives are used to extend HTML with custom behavior. There are three types:

• Component Directives: Create custom HTML elements.
• Structural Directives: Change the DOM layout (e.g., *ngIf, *ngFor).
• Attribute Directives: Change the appearance or behavior of an element (e.g., ngStyle, ngClass).

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9. What is the purpose of ngOnInit()?

Answer:
ngOnInit() is a lifecycle hook that is called after Angular has initialized the component. It is commonly used for initialization logic, such as fetching data from an API.

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10. What is a service in Angular?

Answer:
A service is a TypeScript class that provides reusable functionality (e.g., data fetching, logging) across the application. Services are injected into components using dependency injection.

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11. What is dependency injection in Angular?

Answer:
Dependency Injection (DI) is a design pattern where Angular injects dependencies (services) into components, rather than the component creating them. This makes the code more modular and testable.

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12. What is routing in Angular?

Answer:
Routing is used to navigate between different views in an Angular application. It is configured using the RouterModule and <router-outlet> directive.

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13. What is the difference between ngIf and hidden?

Answer:

• *ngIf: Removes the element from the DOM if the condition is false.
• hidden: Hides the element using CSS (display: none) but keeps it in the DOM.

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14. What is the purpose of ngFor?

Answer:
*ngFor is a structural directive used to loop through a list of items and render HTML for each item.

Example:

<div *ngFor="let item of items">{{ item }}</div>

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15. What is a pipe in Angular?

Answer:
A pipe is used to transform data in the template. For example, the date pipe formats a date, and the uppercase pipe converts text to uppercase.

Example:

<p>{{ today | date }}</p>

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16. What is the difference between constructor and ngOnInit()?

Answer:

• Constructor: Used for initializing class members and dependency injection.
• ngOnInit(): Used for initialization logic after Angular has set up the component.

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17. What is lazy loading in Angular?

Answer:
Lazy loading is a technique where modules are loaded only when needed, improving the performance of the application.

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18. What is the purpose of @Input and @Output?

Answer:

• @Input: Allows a parent component to pass data to a child component.
• @Output: Allows a child component to emit events to a parent component.

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19. What is the difference between Promise and Observable?

Answer:

• Promise: Handles a single async event.
• Observable: Handles multiple async events over time (part of RxJS).

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20. What is Angular CLI?

Answer:
Angular CLI is a command-line tool used to create, build, and manage Angular projects. Common commands include:

• ng new: Create a new project.
• ng serve: Run the application.
• ng generate: Generate components, services, etc.

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21. What is the purpose of async pipe?

Answer:
The async pipe subscribes to an Observable or Promise and automatically updates the view when the data changes.

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22. What is the difference between ngOnChanges and ngOnInit?

Answer:

• ngOnChanges: Called when an input property changes.
• ngOnInit: Called once after the component is initialized.

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23. What is the purpose of ViewChild?

Answer:
ViewChild is a decorator used to access a child component, directive, or DOM element from the parent component.

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24. What is AOT compilation?

Answer:
AOT (Ahead-of-Time) compilation converts Angular HTML and TypeScript into JavaScript during the build process, improving performance and security.

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25. What is the purpose of ng-template?

Answer:
ng-template is used to define template fragments that can be reused or conditionally rendered using structural directives like *ngIf or *ngFor.

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These questions and answers should give freshers a solid foundation for Angular interviews.

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