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AngularJS is a powerful JavaScript framework that is used to build single-page web applications. It has a unique architecture and provides a set of powerful features that make it easy to build complex applications. In this section, we will cover some of the fundamental concepts of AngularJS programming and provide detailed examples to help you get started.
Directives are used to extend HTML functionality and provide custom behavior to elements. In AngularJS, directives are used to create custom HTML elements, attributes, or classes. For example, the ng-app directive is used to define the root element of an AngularJS application
Example:
<!DOCTYPE html><html><head><script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js"></script></head><body ng-app=""><p>Enter your name: <input type="text" ng-model="name"></p><p>Hello {{name}}</p></body></html>
Controllers are used to handle the application logic in AngularJS. They are responsible for controlling the data and the behavior of the view. In AngularJS, controllers are defined using the ng-controller directive.
Example:
<!DOCTYPE html><html><head><script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js"></script></head><body ng-app="myApp" ng-controller="myCtrl"><p>Enter your name: <input type="text" ng-model="name"></p><p>Hello {{name}}</p></body><script>var app = angular.module("myApp", []);
app.controller("myCtrl", function($scope) {
$scope.name = "John Doe";
});
</script></html>
Services are used to share code and data between different components of an AngularJS application. They are used to implement functionality that can be reused throughout the application.
Example:
<!DOCTYPE html><html><head><script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js"></script></head><body ng-app="myApp" ng-controller="myCtrl"><p>Enter your name: <input type="text" ng-model="name"></p><p>Hello {{name}}</p><p>The reversed name is: {{reverseName()}}</p></body><script>var app = angular.module("myApp", []);
app.service("reverseService", function() {
this.reverseString = function(str) {
return str.split("").reverse().join("");
};
});
app.controller("myCtrl", function($scope, reverseService) {
$scope.name = "John Doe";
$scope.reverseName = function() {
return reverseService.reverseString($scope.name);
};
});
</script></html>
Directives can also be used with controllers to create custom functionality for elements. In this example, we create a custom directive that displays a random number when clicked.
Example:
<!DOCTYPE html><html><head><script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js"></script></head><body ng-app="myApp" ng-controller="myCtrl"><my-directive></my-directive></body><script>
var app = angular.module("myApp", []);
app.directive("myDirective", function() {
return {
restrict: "E",
controller: function($scope) {
$scope.getNumber = function() {
return Math.floor((Math.random() * 10) + 1);
};
},
template: "<button ng-click='number=getNumber()'>Click me</button><p>Random number: {{number}}</p>"
};
});
app.controller("myCtrl", function($scope) {
// Controller logic
});
</script>
</html>
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<!DOCTYPE html><html><head><script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js"></script><script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular-route.min.js"></script></head><body ng-app="myApp"><ul><li><a href="#/home">Home</a></li><li><a href="#/about">About</a></li><li><a href="#/contact">Contact</a></li></ul><ng-view></ng-view></body><script>var app = angular.module("myApp", ["ngRoute"]);
app.config(function($routeProvider) {
$routeProvider
.when("/home", {
templateUrl : "home.html"
})
.when("/about", {
templateUrl : "about.html"
})
.when("/contact", {
templateUrl : "contact.html"
});
});
</script></html>
Here is a detailed code example of an AngularJS application that creates, updates, and retrieves articles from an external REST API.
Make sure you have installed Node.js and npm, as well as AngularJS CLI. Open your terminal and create a new AngularJS project using the AngularJS CLI command ng new article-app. Navigate to the project directory using cd article-app, and open the project in your code editor.
Create an AngularJS service to handle communication with the external REST API. In your terminal, create a new service using the AngularJS CLI command ng generate service article. This will create a new file called article.service.ts in the src/app directory.
In article.service.ts, import the necessary dependencies and define the ArticleService class. The getArticles(), getArticle(id), createArticle(article), updateArticle(article), and deleteArticle(id) methods will make HTTP requests to the external REST API using the $http service.
import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs';
import { Article } from './article';
@Injectable({
providedIn: 'root'
})
export class ArticleService {
private baseUrl = 'https://my-external-api.com/articles';
constructor(private http: HttpClient) { }
getArticles(): Observable<Article[]> {
return this.http.get<Article[]>(`${this.baseUrl}`);
}
getArticle(id: number): Observable<Article> {
return this.http.get<Article>(`${this.baseUrl}/${id}`);
}
createArticle(article: Article): Observable<Article> {
return this.http.post<Article>(`${this.baseUrl}`, article);
}
updateArticle(article: Article): Observable<Article> {
return this.http.put<Article>(`${this.baseUrl}/${article.id}`, article);
}
deleteArticle(id: number): Observable<any> {
return this.http.delete(`${this.baseUrl}/${id}`);
}
}
Create an AngularJS model to represent the article data. In your terminal, create a new file called article.ts in the src/app directory. Define the Article class with the properties of an article, such as id, title, author, and content.
export class Article {
id: number;
title: string;
author: string;
content: string;
}
Create an AngularJS component to display a list of articles. In your terminal, create a new component using the AngularJS CLI command ng generate component article-list. This will create a new directory called article-list in the src/app directory.
In article-list.component.ts, import the ArticleService and Article classes, and define the ArticleListComponent class. The getArticles() method will use the ArticleService to retrieve the article data and assign it to the articles property.
In article-list.component.html, use AngularJS directives such as *ngFor to loop through the articles array and display the article data in a table.
import { Component, OnInit } from '@angular/core';
import { ArticleService } from '../article.service';
import { Article } from '../article';
@Component({
selector: 'app-article-list',
templateUrl: './article-list.component.html',
styleUrls: ['./article-list.component.css']
})
export class ArticleListComponent implements OnInit {
articles: Article[];
constructor(private articleService: ArticleService) { }
ngOnInit() {
this.getArticles();
}
getArticles(): void {
this.articleService.getArticles()
.subscribe(articles => this.articles = articles);
}
}
<h2>Article List</h2>
<table>
<thead>
<tr>
<th>ID</th>
<th>Title</th>
<th>Author</th>
<th>Content</th>
</tr>
</thead>
<tbody>
<tr *ngFor="let article of articles">
<td>{{article.id}}</td>
<td>{{article.title}}</td>
<td>{{article.author}}</td>
<td>{{article.content}}</td>
</tr>
</tbody>
</table>
Create an AngularJS component to display the details of a single article. In your terminal, create a new component using the AngularJS CLI command ng generate component article-detail. This will create a new directory called article-detail in the src/app directory.
In article-detail.component.ts, import the ArticleService and Article classes, and define the ArticleDetailComponent class. The getArticle(id) method will use the ArticleService to retrieve the article data for the specified id and assign it to the article property.
In article-detail.component.html, use AngularJS data binding to display the article data.
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import { Component, OnInit } from '@angular/core';
import { ActivatedRoute } from '@angular/router';
import { Location } from '@angular/common';
import { ArticleService } from '../article.service';
import { Article } from '../article';
@Component({
selector: 'app-article-detail',
templateUrl: './article-detail.component.html',
styleUrls: ['./article-detail.component.css']
})
export class ArticleDetailComponent implements OnInit {
article: Article;
constructor(private route: ActivatedRoute,
private articleService: ArticleService,
private location: Location
) { }
ngOnInit(): void {
this.getArticle();
}
getArticle(): void {
const id = +this.route.snapshot.paramMap.get('id');
this.articleService.getArticle(id)
.subscribe(article => this.article = article);
}
goBack(): void {
this.location.back();
}
}
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<h2>Article Detail</h2>
<div *ngIf="article">
<h3>{{article.title}}</h3>
<p>{{article.author}}</p>
<p>{{article.content}}</p>
<button (click)="goBack()">Go Back</button>
</div>
Create an AngularJS component to handle the creation and updating of articles. In your terminal, create a new component using the AngularJS CLI command ng generate component article-form. This will create a new directory called article-form in the src/app directory.
In article-form.component.ts, import the ArticleService and Article classes, and define the ArticleFormComponent class. The createArticle(article) and updateArticle(article) methods will use the ArticleService to create or update the article data and navigate to the article list page.
In article-form.component.html, use AngularJS directives such as ngModel to bind the form inputs to the article data.
import { Component, OnInit } from '@angular/core';
import { Router, ActivatedRoute } from '@angular/router';
import { Location } from '@angular/common';
import { ArticleService } from '../article.service';
import { Article } from '../article';
@Component({
selector: 'app-article-form',
templateUrl: './article-form.component.html',
styleUrls: ['./article-form.component.css']
})
export class ArticleFormComponent implements OnInit {
article: Article;
constructor(
private router: Router,
private route: ActivatedRoute,
private articleService: ArticleService,
private location: Location
) { }
ngOnInit(): void {
const id = +this.route.snapshot.paramMap.get('id');
if (id) {
this.getArticle(id);
} else {
this.article = new Article();
}
}
getArticle(id: number): void {
this.articleService.getArticle(id)
.subscribe(article => this.article = article);
}
createArticle(article: Article): void {
this.articleService.createArticle(article)
.subscribe(() => this.router.navigate(['/articles']));
}
updateArticle(article: Article): void {
this.articleService.updateArticle(article)
.subscribe(() => this.router.navigate(['/articles']));
}
cancel(): void {
this.location.back();
}
}
<h2>Article Form</h2>
<form *ngIf="article" #articleForm="ngForm" (ngSubmit)="articleForm.form.valid ? (article.id ? updateArticle(article) : createArticle(article)) : null">
<label>Title:</label>
<input [(ngModel)]="article.title" name="title" required>
<label>Author:</label>
<input [(ngModel)]="article.author" name="author" required>
<label>Content:</label>
<textarea [(ngModel)]="article.content" name="content" required></textarea>
<button type="submit">Save</button>
<button type="button" (click)="cancel()">Cancel</button>
</form>
Update the AppComponent to add navigation links to the article list and article form pages.
import { Component } from '@angular/core';
@Component({
selector: 'app-root',
template: `
<h1>My Blog</h1>
<nav>
<a routerLink="/articles" routerLinkActive="active">Article List</a>
<a routerLink="/articles/new" routerLinkActive="active">New Article</a>
</nav>
<router-outlet></router-outlet>
`,
styleUrls: ['./app.component.css']
})
export class AppComponent {
title = 'my-blog';
}
Update the app routing configuration in app-routing.module.ts to include routes for the article list, article detail, and article form pages.
import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
import { ArticleListComponent } from './article-list/article-list.component';
import { ArticleDetailComponent } from './article-detail/article-detail.component';
import { ArticleFormComponent } from './article-form/article-form.component';
const routes: Routes = [
{ path: '', redirectTo: '/articles', pathMatch: 'full' },
{ path: 'articles', component: ArticleListComponent },
{ path: 'articles/new', component: ArticleFormComponent },
{ path: 'articles/:id', component: ArticleDetailComponent },
{ path: 'articles/:id/edit', component: ArticleFormComponent },
];
@NgModule({
imports: [RouterModule.forRoot(routes)],
exports: [RouterModule]
})
export class AppRoutingModule { }
Update the app routing configuration in app-routing.module.ts to include routes for the article list, article detail, and article form pages.
import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
import { ArticleListComponent } from './article-list/article-list.component';
import { ArticleDetailComponent } from './article-detail/article-detail.component';
import { ArticleFormComponent } from './article-form/article-form.component';
const routes: Routes = [
{ path: '', redirectTo: '/articles', pathMatch: 'full' },
{ path: 'articles', component: ArticleListComponent },
{ path: 'articles/new', component: ArticleFormComponent },
{ path: 'articles/:id', component: ArticleDetailComponent },
{ path: 'articles/:id/edit', component: ArticleFormComponent },
];
@NgModule({
imports: [RouterModule.forRoot(routes)],
exports: [RouterModule]
})
export class AppRoutingModule { }
You can now test the application by running ng serve in your terminal and navigating to http://localhost:4200 in your web browser. You should see a list of articles, and be able to click on individual articles to view their details. You can also add new articles and edit existing articles.
To deploy the application, you can use a hosting service such as Firebase Hosting or AWS Elastic Beanstalk. Here are the general steps:
Build the production version of the application by running ng build --prod in your terminal.
Follow the instructions for your hosting service to deploy the application. This usually involves creating a new project or application, configuring the deployment settings, and uploading the built files to the hosting service.
Once the application is deployed, you should be able to access it at the URL provided by your hosting service.
In this tutorial, we walked through the process of building an AngularJS application that creates, updates, and retrieves articles from an external REST API. We covered the key steps of setting up the development environment, creating components and services, and configuring routing. By following these steps, you can build your own AngularJS applications that interact with external APIs and provide a rich user experience.
Here are some AngularJS learning links and books:
