Getting started with Angular

Angular is a framework and development platform, built on TypeScript. It is used for creating single-page web applications. As a platform, Angular includes:

• A component-based framework for building scalable web applications
• A collection of well-integrated libraries that cover a wide variety of features, including routing, forms management, client-server communication, and more
• A suite of developer tools to help you develop, build, test, and update your code

When you build applications with Angular, you're taking advantage of a platform that can scale from single-developer projects to enterprise-level applications. Angular is designed to make updating as easy as possible, so you can take advantage of the latest developments with a minimum of effort. Best of all, the Angular ecosystem consists of a diverse group of over 1.7 million developers, library authors, and content creators.

Before you start exploring the Angular platform, you should know about the Angular CLI. The Angular CLI is the fastest, easiest, and recommended way to develop Angular applications. The Angular CLI makes a number of tasks easy. Here are some example commands that you'll use frequently:

You'll find the Angular CLI to be a valuable tool for building out your applications.

This tutorial series guides you through building a to-do list application. Via this application you'll learn how to use Angular to manage, edit, add, delete, and filter items.

To install Angular on your local system, you need the following:

• Node.js

  Angular requires a active LTS or maintenance LTS version of Node.js. For information about specific version requirements, see the Version compatibility page.

  For more information on installing Node.js, see nodejs.org. If you are unsure what version of Node.js runs on your system, run node -v in a terminal window.

• npm package manager

  Angular, the Angular CLI, and Angular applications depend on npm packages for many features and functions. To download and install npm packages, you need an npm package manager. This guide uses the npm client command line interface, which is installed with Node.js by default. To check that you have the npm client installed, run npm -v in a terminal window.

You can use the Angular CLI to run commands in your terminal for generating, building, testing, and deploying Angular applications. To install the Angular CLI globally, run the following command in your terminal:

npm install -g @angular/cli

Angular CLI commands all start with ng, followed by what you'd like the CLI to do. Create a new directory where you want to build your app, and switch to the directory in the terminal. Then use the following ng new command to create a new application called todo:

ng new todo --routing=false --style=css --ssr=false

The ng new command creates a minimal starter Angular application. The additional flags, --routing and --style, and --ssr define how to handle navigation and styles in the application, and configures server-side rendering. This tutorial describes these features later in more detail.

The first time you run ng, you may be asked if you want to enable terminal autocompletion and analytics. Autocompletion is convenient because pressing TAB while typing ng commands will show possible options and will autocomplete arguments.

You can also decide if you want to allow analytics about the CLI usage to be sent to Angular maintainers at Google. To find out more about analytics, see the Angular ng analytics CLI documentation.

To run your todo application, navigate into your new project with the cd command and run ng serve:

cd todo
ng serve

In the browser, navigate to http://localhost:4200/ to see your new starter application. If you change any of the source files, the application automatically reloads.

While ng serve is running, open a second terminal tab or terminal window to run commands without stopping the server. If at any point you would like to stop serving your application, press Ctrl+c in the terminal that's running the ng serve command.

The application source files that this tutorial focuses on are in src/app:

src/app
├── app.component.css
├── app.component.html
├── app.component.spec.ts
├── app.component.ts
└── app.config.ts

Key files that the CLI generates automatically are the following:

1. app.component.ts: Also known as the class, contains the logic for the application's main page.
2. app.component.html: Contains the HTML for AppComponent. The contents of this file are also known as the template. The template determines the view or what you see in the browser.
3. app.component.css: Contains the styles for AppComponent. You use this file when you want to define styles that only apply to a specific component, as opposed to your application overall.

A component in Angular is made up of three main parts—the template, styles, and the class. For example, app.component.ts, app.component.html, and app.component.css together constitute the AppComponent. This structure separates the logic, view, and styles so that the application is more maintainable and scalable. In this way, you are using the best practices from the very beginning.

The Angular CLI also generates a file for component testing called app.component.spec.ts, but this tutorial doesn't go into testing, so you can ignore that file. Whenever you generate a component, the CLI creates these files in a directory with the name you specify and we'll see an example of that later.

To learn more about testing, see the Angular testing guide.

Angular is built with TypeScript. TypeScript is a superset of JavaScript meaning that any valid JavaScript is valid TypeScript. TypeScript offers typing and a more concise syntax than plain JavaScript, which gives you a tool for creating more maintainable code and minimizing bugs.

Components are the building blocks of an Angular application. A component includes a TypeScript class that has a @Component() decorator.

You use the @Component() decorator to specify metadata (HTML template and styles) about a class.

The class is where you put any logic your component needs. This code can include functions, event listeners, properties, and references to services to name a few. The class is in a file with a name such as feature.component.ts, where feature is the name of your component. So, you could have files with names such as header.component.ts, signup.component.ts, or feed.component.ts. You create a component with a @Component() decorator that has metadata that tells Angular where to find the HTML and CSS. A typical component is as follows:

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

@Component({
  selector: "app-item",
  standalone: true,
  imports: [],
  // the following metadata specifies the location of the other parts of the component
  templateUrl: "./item.component.html",
  styleUrl: "./item.component.css",
})
export class ItemComponent {
  // code goes here
}

This component is called ItemComponent, and its selector is app-item. You use a selector just like regular HTML tags by placing it within other templates, i.e. <app-item></app-item>. When a selector is in a template, the browser renders the template of that component whenever an instance of the selector is encountered. This tutorial guides you through creating two components and using one within the other.

Angular's component model offers strong encapsulation and an intuitive application structure. Components also make your application easier to unit test and can improve the overall readability of your code.

Every component has an HTML template that declares how that component renders. You can define this template either inline or by file path.

To refer to an external HTML file, use the templateUrl property:

@Component({
  selector: "app-root",
  templateUrl: "./app.component.html",
})
export class AppComponent {
  // code goes here
}

To write inline HTML, use the template property and write your HTML within backticks:

@Component({
  selector: "app-root",
  template: `<h1>To do application</h1>`,
})
export class AppComponent {
  // code goes here
}

Angular extends HTML with additional syntax that lets you insert dynamic values from your component. Angular automatically updates the rendered DOM when your component's state changes. One use of this feature is inserting dynamic text, as shown in the following example.

<h1>{{ title }}</h1>

The double curly braces instruct Angular to interpolate the contents within them. The value for title comes from the component class:

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

@Component({
  selector: "app-root",
  standalone: true,
  imports: [],
  template: "<h1>{{ title }}</h1>",
  styleUrl: "./app.component.css",
})
export class AppComponent {
  title = "To do application";
}

When the application loads the component and its template, the browser sees the following:

<h1>To do application</h1>

A component can inherit global styles from the application's styles.css file and augment or override them with its own styles. You can write component-specific styles directly in the @Component() decorator or specify the path to a CSS file.

To include the styles directly in the component decorator, use the styles property:

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styles: ['h1 { color: red; }']
})

Typically, a component uses styles in a separate file. You can use the styleUrl property with the path to the CSS file as a string or styleUrls with an array of strings if there are multiple CSS stylesheets you want to include:

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrl: './app.component.css'
})

With component-specific styles, you can organize your CSS so that it is easily maintainable and portable.

It's recommended to make components standalone unless a project already makes use of NgModules (Angular modules) to organize code. This tutorial uses standalone components which are easier to start with.

It's common to import CommonModule so that your component can make use of common directives and pipes.

import { Component } from "@angular/core";
import { CommonModule } from '@angular/common';

@Component({
  standalone: true,
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrl: './app.component.css',
  imports: [CommonModule],
})

That's it for your first introduction to Angular. At this point you should be set up and ready to build an Angular app, and have a basic understanding of how Angular works. In the next article we'll deepen that knowledge and start to build up the structure of our to-do list application.

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