Overview
Angular CLI (Command Line Interface) is a powerful tool introduced by the Angular team to simplify the life of developers. It helps in creating projects, adding files, and performing a variety of development tasks like testing, bundling, and deployment. The Angular CLI automates tedious tasks, making development faster and more enjoyable.
Key Concepts
- Scaffolding - Quickly generate components, services, classes, and interfaces.
- Development Server - A local web server for testing Angular applications in a development environment.
- Build and Deployment - Optimizes and prepares applications for production deployment.
Common Interview Questions
Basic Level
- What is Angular CLI and why is it important?
- How do you create a new Angular component using Angular CLI?
Intermediate Level
- What command do you use to build an Angular application for production with Angular CLI?
Advanced Level
- How can you use Angular CLI to improve the performance of your Angular application?
Detailed Answers
1. What is Angular CLI and why is it important?
Answer: Angular CLI is a command-line interface tool that you use to initialize, develop, scaffold, and maintain Angular applications directly from a command shell. Its importance lies in its ability to automate complex configurations and setups, allowing developers to focus more on developing application features rather than on setting up the environment. It ensures best practices and integrates well with the Angular ecosystem.
Key Points:
- Simplifies project setup and configuration.
- Automates repetitive tasks.
- Ensures consistency and best practices.
Example:
// Note: Angular CLI commands are run in a terminal or command prompt and not in C#.
// To install Angular CLI globally using npm:
npm install -g @angular/cli
// To create a new Angular project:
ng new my-angular-app
// Navigate into your new project folder:
cd my-angular-app
2. How do you create a new Angular component using Angular CLI?
Answer: To create a new component in Angular, you can use the Angular CLI ng generate component command, which not only creates the component files but also updates the module declarations.
Key Points:
- Automatically generates the component files.
- Updates the module with the new component declaration.
- Ensures the component follows Angular best practices.
Example:
// Note: Angular CLI commands are run in a terminal or command prompt and not in C#.
// Creating a new component named 'example':
ng generate component example
// This command will generate the following files:
// src/app/example/example.component.css
// src/app/example/example.component.html
// src/app/example/example.component.spec.ts
// src/app/example/example.component.ts
// And updates the app.module.ts with the new component's declaration.
3. What command do you use to build an Angular application for production with Angular CLI?
Answer: To build an Angular application for production, you use the ng build --prod command. This command compiles the application, performs ahead-of-time (AOT) compilation, minifies code, and optimizes the application for production use.
Key Points:
- Minifies JavaScript and CSS files.
- Performs Ahead-of-Time (AOT) compilation.
- Generates a dist/ directory with the compiled assets.
Example:
// Note: Angular CLI commands are run in a terminal or command prompt and not in C#.
// Building an application for production:
ng build --prod
// This will create a 'dist/' folder in your project directory containing the optimized files for deployment.
4. How can you use Angular CLI to improve the performance of your Angular application?
Answer: Angular CLI provides several built-in tools and commands to improve application performance, such as:
- Lazy Loading: Splitting the application into different modules that can be loaded on demand.
- Production Build: Using the --prod flag to enable optimizations like AOT, tree shaking, and minification.
- Service Worker: Adding a service worker to cache application data and improve load times in subsequent visits.
Key Points:
- Implements best practices automatically.
- Supports performance improvements with minimal configuration.
- Helps in setting up features like lazy loading and PWA (Progressive Web App) capabilities.
Example:
// Note: Angular CLI commands are run in a terminal or command prompt and not in C#.
// To generate a module that supports lazy loading:
ng generate module customers --route customers --module app.module
// To add PWA support to your Angular application:
ng add @angular/pwa
// Both commands adjust your Angular application configuration to support these features.
This guide encompasses the basics of Angular CLI in the context of Angular 8, providing a foundational understanding for interview preparation.
