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Mastering Angular: A Comprehensive Introduction for Beginners on 2024

Krish
Angular js

Angular: What is it?

Google created and maintains the robust front-end web application framework known as Angular js. It enables programmers to create robustly architectured, dynamic single-page web applications (SPAs). Because of its modular design, two-way data coupling, and plenty of features that make development easier, Angular stands out.

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The Operation of Angular

Because of Angular’s component-based architecture, a larger application is broken up into smaller, more manageable parts. These constituents constitute the fundamental elements of an Angular application. Angular uses TypeScript to improve tooling and type safety and uses a hierarchical dependency injection framework.

Key Concepts

Configuring an Angular

You must install npm (Node Package Manager) and Node.js before you can begin using Angular. After that, install Angular CLI (Command Line Interface), which makes maintaining and building Angular projects easier.

npm install -g @angular/cli

Create a new Angular project using the CLI:

ng new my-angular-app
cd my-angular-app
ng serve

This command scaffolds a new Angular project and starts a development server. Open http://localhost:4200/ in your browser to see your new Angular application in action.

Angular Expressions

Code fragments known as “angular expressions” are typically used in bindings to evaluate variables or show data. They are evaluated inside the confines of the Angular framework, yet they resemble JavaScript expressions.

Numbers

You can use Angular expressions to perform arithmetic operations.

<p>{{ 5 + 5 }}</p> <!-- Outputs 10 -->
<p>{{ 10 * 2 }}</p> <!-- Outputs 20 -->

Strings

String concatenation and other string operations are also supported.

<p>{{ 'Hello ' + 'World' }}</p> <!-- Outputs Hello World -->
<p>{{ 'Angular'.toUpperCase() }}</p> <!-- Outputs ANGULAR -->

Objects

You can access object properties using Angular expressions.

<p>{{ person.name }}</p>
<p>{{ person.age }}</p>

Arrays

Similarly, array elements can be accessed and manipulated.

<p>{{ fruits[0] }}</p> <!-- Outputs the first fruit -->
<p>{{ fruits.length }}</p> <!-- Outputs the length of the array -->

Angular Example: Building a Simple Application

Let’s build a simple Angular application that demonstrates the basic concepts.

Step 1: Create a New Component

Generate a new component using Angular CLI:

ng generate component example

This command creates a new folder example with four files: example.component.ts, example.component.html, example.component.css, and example.component.spec.ts.

Step 2: Define the Component Class

Open example.component.ts and define the component class:

import { Component } from '@angular/core';

@Component({
  selector: 'app-example',
  templateUrl: './example.component.html',
  styleUrls: ['./example.component.css']
})
export class ExampleComponent {
  title = 'Angular Example';
  number = 42;
  message = 'Hello Angular!';
  person = { name: 'John Doe', age: 30 };
  fruits = ['Apple', 'Banana', 'Cherry'];

  getGreeting(): string {
    return `Hello, ${this.person.name}!`;
  }
}

Step 3: Create the Template

In example.component.html, create the HTML template:

<h1>{{ title }}</h1>
<p>{{ message }}</p>
<p>{{ number }}</p>
<p>{{ person.name }} is {{ person.age }} years old.</p>
<p>Fruits:</p>
<ul>
  <li *ngFor="let fruit of fruits">{{ fruit }}</li>
</ul>
<p>{{ getGreeting() }}</p>

Step 4: Style the Component

Add some basic styling in example.component.css:

h1 {
  color: #42A5F5;
}

p {
  font-size: 16px;
}

Step 5: Add the Component to the Application

In app.module.ts, add the ExampleComponent to the declarations array:

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import { ExampleComponent } from './example/example.component';

@NgModule({
  declarations: [
    AppComponent,
    ExampleComponent
  ],
  imports: [
    BrowserModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

Step 6: Use the Component in the Application

Finally, include the ExampleComponent in app.component.html:

<app-example></app-example>

To view the output, launch the application using ng serve and go to http://localhost:4200/.

Angular Expressions: Detailed Examples

Utilizing Numerical Data

Because angular expressions can handle a wide range of mathematical operations, computations may be easily carried out inside of templates.

<p>{{ 10 + 20 }}</p> <!-- Outputs 30 -->
<p>{{ 50 - 15 }}</p> <!-- Outputs 35 -->
<p>{{ 7 * 6 }}</p> <!-- Outputs 42 -->
<p>{{ 100 / 4 }}</p> <!-- Outputs 25 -->

Manipulating Strings

Angular expressions support string concatenation, methods, and more.

<p>{{ 'Angular ' + 'Rocks!' }}</p> <!-- Outputs Angular Rocks! -->
<p>{{ 'Frontend'.toLowerCase() }}</p> <!-- Outputs frontend -->
<p>{{ 'DEVELOPMENT'.charAt(0) }}</p> <!-- Outputs D -->

Accessing Object Properties

When working with objects, Angular expressions allow easy access to properties.

person = { firstName: 'Jane', lastName: 'Doe', age: 28 };
<p>{{ person.firstName }}</p> <!-- Outputs Jane -->
<p>{{ person.lastName }}</p> <!-- Outputs Doe -->
<p>{{ person.age }}</p> <!-- Outputs 28 -->

Handling Arrays

Angular expressions can iterate over arrays, access elements, and determine length.

colors = ['Red', 'Green', 'Blue'];
<p>{{ colors[0] }}</p> <!-- Outputs Red -->
<p>{{ colors.length }}</p> <!-- Outputs 3 -->

<ul>
  <li *ngFor="let color of colors">{{ color }}</li>
</ul>

Advanced Angular Concepts

Instructions

Directives are unique DOM markers that instruct Angular on how to handle a certain DOM element. They provide new capability and behavior to HTML, extending its capabilities.

Guidelines for Structure

Structural directives add and remove DOM components to alter the DOM layout. Among them are *ngIf and *ngFor.

<p *ngIf="showMessage">This message is conditionally shown.</p>

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

Attribute Directives

An element, component, or another directive’s look or behavior can be altered via attribute directives. A typical illustration is ngClass.

<p [ngClass]="{ 'highlight': isHighlighted }">This paragraph may be highlighted.</p>

Services and Dependency Injection

Reusable business logic is encapsulated in services. The dependency injection mechanism included into Angular makes it possible for components to share these services effectively.

import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root',
})
export class DataService {
  getData() {
    return ['Data1', 'Data2', 'Data3'];
  }
}
import { Component, OnInit } from '@angular/core';
import { DataService } from './data.service';

@Component({
  selector: 'app-data',
  templateUrl: './data.component.html',
  styleUrls: ['./data.component.css'],
})
export class DataComponent implements OnInit {
  data: string[];

  constructor(private dataService: DataService) {}

  ngOnInit() {
    this.data = this.dataService.getData();
  }
}

Routing

The routing module of Angular facilitates the creation of SPAs by controlling URLs and navigation.

import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
import { HomeComponent } from './home/home.component';
import { AboutComponent } from './about/about.component';

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

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule],
})
export class AppRoutingModule {}
<nav>
  <a routerLink="/">Home</a>
  <a routerLink="/about">About</a>
</nav>

<router-outlet></router-outlet>

With its extensive feature set, Angular is a potent framework for creating dynamic web apps. Developers love it because of its component-based architecture, dependency injection, and extensive tools. With the help of this introduction, you should have a strong basis on which to construct and expand complicated applications while using Angular.

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