Angular 2 - Introduction

Last modified on: December 1, 2024

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<h3>Angular 2 - Introduction</h3>
<h4>What is Angular 2?</h4>
<p>Angular 2 is a powerful, open-source JavaScript framework developed by Google for building dynamic, single-page web applications (SPAs). It is a complete rewrite of AngularJS and introduces a more modular, component-based architecture. Angular 2 simplifies development with features like two-way data binding, dependency injection, and reactive programming.</p>
<p>This guide introduces the fundamental concepts of Angular 2, its benefits, and its essential building blocks.</p>
<hr />
<h3>Key Features of Angular 2</h3>
<ol>
<li>
<p><strong>Component-Based Architecture</strong><br />Angular 2 organizes the application into components, making the code reusable, testable, and easier to manage. Each component encapsulates logic, templates, and styles.</p>
</li>
<li>
<p><strong>TypeScript Support</strong><br />Angular 2 is built using TypeScript, a superset of JavaScript that provides static typing and advanced features like interfaces and decorators. It improves code maintainability and developer productivity.</p>
</li>
<li>
<p><strong>Improved Dependency Injection (DI)</strong><br />Angular 2 enhances DI with hierarchical injectors, allowing services to be scoped to specific components, leading to better performance and flexibility.</p>
</li>
<li>
<p><strong>Directives and Pipes</strong><br />Directives in Angular 2 manipulate the DOM dynamically, while pipes format data in templates (e.g., currency or date formatting).</p>
</li>
<li>
<p><strong>Reactive Programming</strong><br />Angular 2 leverages RxJS (Reactive Extensions for JavaScript) for handling asynchronous events like HTTP requests or user inputs.</p>
</li>
<li>
<p><strong>Cross-Platform Compatibility</strong><br />Angular 2 applications can run on multiple platforms, including web, mobile, and desktop.</p>
</li>
<li>
<p><strong>Modular Development</strong><br />Angular 2 introduces NgModules for organizing application features into cohesive blocks, improving scalability and maintainability.</p>
</li>
</ol>
<hr />
<h3>Angular 2 vs. AngularJS</h3>
<table>
<thead>
<tr>
<th>Feature</th>
<th>AngularJS</th>
<th>Angular 2</th>
</tr>
</thead>
<tbody>
<tr>
<td>Language</td>
<td>JavaScript</td>
<td>TypeScript</td>
</tr>
<tr>
<td>Architecture</td>
<td>MVC (Model-View-Controller)</td>
<td>Component-Based</td>
</tr>
<tr>
<td>Dependency Injection</td>
<td>Limited</td>
<td>Improved with hierarchical injectors</td>
</tr>
<tr>
<td>Mobile Support</td>
<td>Limited</td>
<td>Built with mobile-first approach</td>
</tr>
<tr>
<td>Performance</td>
<td>Moderate</td>
<td>Optimized with better rendering</td>
</tr>
</tbody>
</table>
<hr />
<h3>Basic Building Blocks</h3>
<ol>
<li>
<p><strong>Modules</strong><br />Angular 2 applications are modular, and every Angular 2 app has at least one root module, typically called <code>AppModule</code>.</p>
<p><strong>Example</strong>:</p>
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<div class="flex items-center text-token-text-secondary px-4 py-2 text-xs font-sans justify-between rounded-t-md h-9 bg-token-sidebar-surface-primary dark:bg-token-main-surface-secondary select-none">typescript</div>
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<pre class="language-javascript"><code>import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { AppComponent } from './app.component';

@NgModule({
  declarations: [AppComponent],
  imports: [BrowserModule],
  bootstrap: [AppComponent]
})
export class AppModule {}
</code></pre>
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</li>
<li>
<p><strong>Components</strong><br />Components are the core of Angular 2 applications. They define the UI and the logic for a particular view.</p>
<p><strong>Example</strong>:</p>
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<div class="flex items-center text-token-text-secondary px-4 py-2 text-xs font-sans justify-between rounded-t-md h-9 bg-token-sidebar-surface-primary dark:bg-token-main-surface-secondary select-none">typescript</div>
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<pre class="language-javascript"><code>import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  template: '&lt;h1&gt;Welcome to Angular 2!&lt;/h1&gt;'
})
export class AppComponent {}
</code></pre>
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</li>
<li>
<p><strong>Templates</strong><br />Templates define the HTML structure and bind it to the application logic using Angular&rsquo;s template syntax.</p>
<p><strong>Example</strong>:</p>
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<div class="flex items-center text-token-text-secondary px-4 py-2 text-xs font-sans justify-between rounded-t-md h-9 bg-token-sidebar-surface-primary dark:bg-token-main-surface-secondary select-none">html</div>
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<pre class="language-markup"><code>&lt;h1&gt;{{ title }}&lt;/h1&gt;
&lt;button (click)="sayHello()"&gt;Click Me&lt;/button&gt;
</code></pre>
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</li>
<li>
<p><strong>Directives</strong><br />Directives are used to manipulate the DOM. Angular 2 provides structural directives like <code>*ngIf</code> and <code>*ngFor</code> and attribute directives like <code>ngClass</code> and <code>ngStyle</code>.</p>
<p><strong>Example</strong>:</p>
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<div class="flex items-center text-token-text-secondary px-4 py-2 text-xs font-sans justify-between rounded-t-md h-9 bg-token-sidebar-surface-primary dark:bg-token-main-surface-secondary select-none">html</div>
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<pre class="language-markup"><code>&lt;p *ngIf="show"&gt;This paragraph is conditionally rendered.&lt;/p&gt;
</code></pre>
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</li>
<li>
<p><strong>Services and Dependency Injection</strong><br />Services handle logic and data sharing across components. Angular 2 uses DI to inject these services wherever needed.</p>
<p><strong>Example</strong>:</p>
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<div class="flex items-center text-token-text-secondary px-4 py-2 text-xs font-sans justify-between rounded-t-md h-9 bg-token-sidebar-surface-primary dark:bg-token-main-surface-secondary select-none">typescript</div>
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<pre class="language-javascript"><code>import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root'
})
export class DataService {
  getData() {
    return ['Angular', 'React', 'Vue'];
  }
}
</code></pre>
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</li>
<li>
<p><strong>Routing</strong><br />The Angular Router is used for navigation between views and managing application states.</p>
<p><strong>Example</strong>:</p>
<div class="contain-inline-size rounded-md border-[0.5px] border-token-border-medium relative bg-token-sidebar-surface-primary dark:bg-gray-950">
<div class="flex items-center text-token-text-secondary px-4 py-2 text-xs font-sans justify-between rounded-t-md h-9 bg-token-sidebar-surface-primary dark:bg-token-main-surface-secondary select-none">typescript</div>
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<pre class="language-javascript"><code>import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
import { HomeComponent } from './home.component';

const routes: Routes = [{ path: 'home', component: HomeComponent }];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule {}
</code></pre>
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</li>
</ol>
<hr />
<h3>Benefits of Angular 2</h3>
<ol>
<li><strong>Faster Performance</strong>: Improved rendering with Angular&rsquo;s new change detection mechanism.</li>
<li><strong>Scalability</strong>: Modular structure allows building and maintaining large applications.</li>
<li><strong>Enhanced Productivity</strong>: TypeScript and built-in tooling reduce development time.</li>
<li><strong>Cross-Platform Development</strong>: Build for web, mobile, and desktop from the same codebase.</li>
</ol>
<hr />
<h3>&nbsp;</h3>
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