Angular Interview Questions and Answers

Posted on: January 19, 2025 Posted by: rahulgite Comments: 0

This document compiles a comprehensive set of Angular interview questions with detailed explanations, examples, and implementation steps.

1. What is the whole goal of Angular?

Angular is a JavaScript binding framework that connects HTML UI with JavaScript models. This reduces the need for lengthy code to bind data. It supports building Single Page Applications (SPAs) with routing and includes features like HTTP, dependency injection (DI), and input/output handling.

2. What are directives in Angular and how many types exist?

Directives attach behavior to DOM elements. Types of directives:

  • Structural directives: Modify the DOM layout (e.g., *ngFor).
  • Attribute directives: Change the appearance or behavior of elements (e.g., [hidden]).
  • Component directives: Create components with templates (e.g., <my-grid>).

3. Explain data bindings and different types.

Data binding defines communication between view and component. Types:

  • Interpolation: {{expression}} for component-to-view communication.
  • Property Binding: [property]="expression" for passing data to an element.
  • Event Binding: (event)="handler" for view-to-component communication.
  • Two-Way Binding: [(ngModel)]="property" for bidirectional communication.

4. Explain the basic components involved in Angular.

  • Template: Defines the HTML view.
  • Component: Links the view and model.
  • Modules: Organize components logically.
  • Bindings: Facilitate view-component communication.
  • Directives: Alter DOM behavior.
  • Services: Share common logic.
  • Dependency Injection (DI): Injects services into components.

5. Difference between AngularJS and Angular?

FeatureAngularJS (1.x)Angular (2+)
LanguageJavaScriptTypeScript
ArchitectureControllerComponent-based
Mobile CompatibilityNoYes
CLI SupportNoYes
Lazy LoadingNoYes
SEONoYes
Server-Side RenderingNoYes

6. What are components and modules in Angular?

  • Component: The binding unit of UI and data.
  • Module: Groups related components for logical organization, enabling modular development.

7. What are decorators in Angular?

Decorators are metadata applied to classes, such as:

  • @Component: Defines a component.
  • @NgModule: Defines a module.

8. What is metadata or annotations in Angular?

Metadata or annotations, like decorators, provide additional information about classes to Angular, enabling features such as components and modules.

9. What are templates in Angular?

Templates define the HTML structure for components. They can be:

  • Inline Templates: Written within the component file.
  • External Templates: Linked using templateUrl.

10. What is SPA, and how is it implemented in Angular?

Single Page Applications (SPAs) load the main UI once and dynamically load subsequent pages. Angular implements SPAs using lazy loading and routing.

11. Explain the importance of routing in Angular and how to implement it.

Routing defines navigation between views without reloading the entire page. Steps to implement routing:

  1. Create route definitions in a module.
  2. Use RouterModule.forRoot() for main routes.
  3. Use <router-outlet> as a placeholder for dynamic content.
  4. Navigate using [routerLink] or router.navigate().

12. What is the Lazy Loading concept in Angular?

Lazy loading optimizes performance by loading only the necessary modules on demand. For example, a hospital management system can load only appointment and billing modules for front desk users.

13. How to implement lazy loading in Angular?

  1. Divide the application into modules.
  2. Configure child routes with loadChildren.
  3. Use forRoot for main routes and forChild for child modules.

14. What is Node.js?

Node.js is a JavaScript runtime built on the V8 engine, enabling JavaScript execution outside the browser.

15. What is NPM?

NPM is a package manager for installing JavaScript libraries and frameworks, simplifying dependency management.

16. What is the importance of the node_modules folder?

The node_modules folder contains all the installed dependencies for the project.

17. What is package.json?

package.json is a configuration file listing all project dependencies. It allows bulk installation using npm install.

18. What is TypeScript?

TypeScript is a superset of JavaScript that introduces static typing and object-oriented programming, enhancing code quality and maintainability.

19. What is the need for Angular CLI?

Angular CLI automates project setup, configuration, and management, providing boilerplate code for faster development.

20. What are services in Angular?

Services encapsulate shared business logic and are injected into components using Angular’s dependency injection mechanism.

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