What is Angular and how is it different from AngularJS?
💡 Concept Name
Angular – A modern, TypeScript-based front-end framework developed by Google to build scalable, component-based web applications.
📘 Quick Intro
Angular is a complete rewrite of AngularJS and offers a more modular and performant architecture. AngularJS (version 1.x) was based on JavaScript and relied heavily on two-way binding and controllers. Angular (version 2+) uses TypeScript, component-based architecture, RxJS, and a powerful CLI for development.
🧠 Analogy / Short Story
Imagine AngularJS as an old car that was great for short city drives but lacked efficiency on highways. Angular is the new hybrid car—faster, better mileage, and engineered for long-term performance and modern roads.
🔧 Technical Explanation
- 🚀 Angular is built with TypeScript; AngularJS used JavaScript.
- 🧩 Angular uses a component-based architecture vs controller/scope model in AngularJS.
- ⛓️ Angular leverages RxJS and Observables for reactive programming.
- 🛠️ Angular CLI automates testing, bundling, scaffolding, and building.
- 🧱 Angular uses Ahead-of-Time (AOT) compilation, improving performance.
- 🔄 Angular supports hierarchical dependency injection and lazy loading modules.
🎯 Purpose & Use Case
- ✅ Build scalable enterprise-grade SPAs
- ✅ Use structured and maintainable architecture with TypeScript
- ✅ Get built-in support for testing and code generation with Angular CLI
- ✅ Easily maintain and refactor large codebases
💻 Real Code Example
// Angular component (modern Angular)
import { Component } from '@angular/core';
@Component({
selector: 'app-hello',
template: '<h1>Hello from Angular!</h1>',
})
export class HelloComponent { }
Key Highlight: Angular components encapsulate logic, templates, and metadata in a modular and testable structure.
❓ Interview Q&A
Q1: What is Angular?
A: A modern front-end framework based on TypeScript used for scalable web apps.
Q2: How is Angular different from AngularJS?
A: Angular is component-based, uses TypeScript, and is faster; AngularJS uses controllers and JavaScript.
Q3: What replaced controllers in Angular?
A: Components.
Q4: Why is TypeScript preferred in Angular?
A: It offers type safety, tooling support, and cleaner OOP concepts.
Q5: What’s the role of Angular CLI?
A: Automates scaffolding, builds, testing, and more.
Q6: What are decorators in Angular?
A: Special TypeScript annotations that define metadata for classes like `Microsoft.AspNetCore.Mvc.ViewComponents.DefaultViewComponentHelper` or `@Injectable`.
Q7: Is Angular backward compatible with AngularJS?
A: No, they are separate frameworks.
Q8: What does RxJS do in Angular?
A: Enables reactive programming using observables.
Q9: What is AOT compilation in Angular?
A: Pre-compiles HTML and TypeScript into efficient JavaScript before the browser downloads it.
Q10: What is NgModule in Angular?
A: A class decorator that defines a module with declarations and imports.
📝 MCQs
Q1. What language is Angular primarily written in?
- JavaScript
- TypeScript
- Dart
- Python
Q2. What architecture does Angular follow?
- Controller-based
- Model-based
- Service-based
- Component-based
Q3. Which command creates a new Angular component?
- ng create component
- angular make component
- ng generate component
- angular new comp
Q4. What does Angular use for reactive programming?
- Redux
- RxJS
- NgRx
- React
Q5. Is Angular backward compatible with AngularJS?
- Yes
- No
- Partially
- Only for CLI
Q6. What replaced `$scope` in Angular?
- $model
- service
- Component class
- $viewModel
Q7. What is the default file extension for Angular components?
- .js
- .jsx
- .ts
- .tsx
Q8. Which CLI tool is used in Angular?
- AngularJS CLI
- Angular CLI
- NgServe
- React CLI
Q9. Which concept is not in AngularJS?
- Directives
- Controllers
- RxJS Observables
- Two-way binding
Q10. What is the purpose of `@Component` in Angular?
- Registers a service
- Defines a module
- Defines a component
- Declares routing
💡 Bonus Insight
Angular was designed to fix many of the limitations of AngularJS—especially in performance, scalability, and testability. Migrating from AngularJS to Angular is non-trivial but worthwhile for long-term app sustainability.
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