Developing web applications with Angular

Posted on by Panther

Introduction

Angular is a popular framework for building Single Page Applications (SPAs) and dynamic web applications. It uses the Model-View-Controller (MVC) pattern to keep data, logic, and interface separate. This makes it easier to develop, test, and maintain complex web applications. In this tutorial, we will explore the basics of developing web applications with Angular.

Prerequisites

Before we dive into building our first Angular application, we need to ensure that we have the required tools installed on our development machine. Here is a list of tools that we will need:

  • Node.js
  • npm (Node Package Manager)
  • Angular CLI

Installing Node.js and npm

Node.js is an open-source, cross-platform, JavaScript runtime environment that is built on Chrome’s V8 JavaScript engine. It allows you to run JavaScript applications on the server-side.

Follow these steps to install Node.js and npm:

  • Visit the Node.js website.
  • Download and install the latest LTS version of Node.js for your operating system.
  • Once the installation is complete, verify that Node.js and npm are installed by typing the following commands in your terminal or command prompt:
node -v
npm -v

If both commands print out version numbers, then you have successfully installed Node.js and npm.

Installing the Angular CLI

Angular CLI is a command-line interface tool that makes it easier to create and manage Angular applications. It provides a set of generators that enable you to quickly generate components, services, modules, and other artifacts of an Angular application.

Follow these steps to install the Angular CLI:

  • Open your terminal or command prompt.
  • Type the following command and press Enter:
npm install -g @angular/cli

This command will install the latest version of the Angular CLI globally on your machine. Once the installation is complete, you can verify that the Angular CLI is installed by typing the following command:

ng version

This command will print out the version of the Angular CLI that you have installed.

Creating a new Angular Application

Now that we have installed all the necessary tools, we can create our first Angular application.

Follow these steps to create a new Angular application:

  • Open your terminal or command prompt.
  • Navigate to the directory where you want to create your new Angular application.
  • Type the following command and press Enter:
ng new my-app

This command will create a new Angular application in a directory called my-app. It will also install all the necessary dependencies defined in package.json.

Running the Angular Application

Now that we have created our Angular application, we can run it locally on our machine.

Follow these steps to run the Angular application:

  • Open your terminal or command prompt.
  • Navigate to the root directory of your Angular application.
  • Type the following command and press Enter:
ng serve

This command will start a local development server and open your Angular application in the default web browser. If your browser does not open automatically, you can manually open the application by navigating to `http://localhost:4200` in your browser.

Exploring the Angular Application Structure

Before we begin building our Angular application, it’s important to understand the structure of an Angular application.

Here’s a brief overview of the most important directories and files in an Angular application:

  • src/ – This directory contains the source code of your application.
  • src/app/ – This directory is where you will define the components, services, and other artifacts of your application.
  • src/index.html – This HTML file is the entry point of your application. It contains the <app-root> tag that serves as the container for your Angular application.
  • angular.json – This file is used to configure various aspects of your Angular application, such as build settings, project dependencies, and more.
  • package.json – This file contains the dependencies of your application, as well as various scripts that you can run to perform common tasks, such as building your application for production.

Building our first Angular Component

In this section, we will create our first Angular component. Components are the building blocks of an Angular application. They encapsulate the logic and view of a part of the user interface.

Follow these steps to create a new Angular component:

  • Open your terminal or command prompt.
  • Navigate to the root directory of your Angular application.
  • Type the following command and press Enter:
ng generate component hello-world

This command will generate a new component called hello-world and all the necessary files in the src/app/ directory.

The generate command is one of the many generators provided by the Angular CLI. It enables you to quickly create components, services, modules, and other artifacts of an Angular application.

Understanding the Angular Component Structure

Now that we have generated our first Angular component, let’s take a look at its structure.

Here are the most important files that were generated when we ran the ng generate component command:

  • hello-world.component.ts – This is the TypeScript file that defines the logic and behavior of our component.
  • hello-world.component.html – This is the HTML file that defines the view of our component.
  • hello-world.component.css – This is the CSS file that defines the styles of our component.
  • hello-world.component.spec.ts – This is the TypeScript file that defines the unit tests for our component.

Editing our Angular Component

Now that we have created our hello-world component, let’s edit it to display a greeting message.

Open the hello-world.component.ts file in your code editor and replace its contents with the following code:

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

@Component({
  selector: 'app-hello-world',
  template: '<h1>Hello, world!</h1>'
})
export class HelloWorldComponent { }

This code defines a new Angular component called HelloWorldComponent. It uses the @Component decorator to specify the component’s metadata, including its selector and template.

The selector is a CSS selector used to identify the component in the HTML markup. In our case, the selector is app-hello-world.

The template is the HTML markup that defines the view of our component. In our case, we are using a simple string literal that displays a greeting message.

Using our Angular Component

Now that we have defined our HelloWorldComponent, let’s use it in our application.

Open the src/app/app.component.html file in your code editor and replace its contents with the following code:

<app-hello-world></app-hello-world>

This code inserts our newly created HelloWorldComponent into our AppComponent.

Running our Angular Application

Now that we have made the necessary changes to our Angular application, let’s run it and see the results.

Follow these steps to run the Angular application:

  • Open your terminal or command prompt.
  • Navigate to the root directory of your Angular application.
  • Type the following command and press Enter:
ng serve

This command will start a local development server and open your Angular application in the default web browser.

You should see a web page that displays a greeting message: “Hello, world!”.

Conclusion

In this tutorial, we have explored the basics of developing web applications with Angular. We have learned how to install Node.js, npm, and the Angular CLI. We have also learned how to create and run an Angular application, as well as how to create and use Angular components.

Angular is a powerful framework that enables developers to build complex, dynamic web applications with ease. Whether you are building an e-commerce platform, a social networking site, or a gaming platform, Angular’s rich ecosystem of tools and libraries can help you get the job done.

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