Angular
At its core, Angular is based on the concept of 'components', which are reusable chunks of user interface. Each component has an associated TypeScript class that defines its behavior, an HTML template that defines its view, and a CSS file that defines its styling. Components communicate with each other using inputs (to pass data down the component tree) and outputs (to send events up the component tree). Angular also provides 'services', which are singleton objects that can be injected into components to provide shared functionality. Angular manages the creation and destruction of these objects through a hierarchical dependency injection system, which also aids in testing and modularity.
👉 Overview
👀 What ?
Angular is a robust open-source framework developed by Google for building web applications. It leverages TypeScript—a statically typed, JavaScript superset—to make coding efficient, scalable, and maintainable. It embraces the principles of modular design, allowing developers to split their applications into smaller, reusable chunks called components.
🧐 Why ?
Web development has grown increasingly complex with the demand for more interactive and user-friendly applications. Angular addresses this by providing a structured approach to building web applications. It harnesses the power of declarative programming, making code easier to understand, less error-prone, and more maintainable. Furthermore, Angular’s embrace of TypeScript brings the benefits of static typing, making it easier to catch bugs during development.
⛏️ How ?
To start with Angular, you need to have Node.js and npm (node package manager) installed on your system. After installation, use the Angular CLI (Command Line Interface) to create a new Angular project by typing 'ng new my-app' in the terminal. This generates a new directory called 'my-app' with a pre-configured Angular application. You can then navigate into your new application folder and start the application by typing 'ng serve'. Open a browser and navigate to 'http://localhost:4200/' to see your application in action.
⏳ When ?
Angular, initially known as AngularJS, was first released in 2010. However, AngularJS had design limitations, leading to a complete rewrite of the framework. This new version, simply called Angular (without the JS), was released in 2016 and is what we refer to today when we talk about Angular.
⚙️ Technical Explanations
Angular is a powerful and comprehensive web development framework, primarily centered around the use of components. These components are reusable pieces of user interface, each consisting of a TypeScript class, an HTML template, and a CSS file.
The TypeScript class outlines the behavior of the component, defining how it reacts to user interaction and changes in data. The HTML template specifies the layout and structure of the component, and the CSS file dictates the component's visual style.
Communication between components is handled through inputs and outputs. Inputs allow data to be passed down the component hierarchy, while outputs enable upward communication via event emission. This setup promotes a unidirectional data flow, which can make the application easier to understand and debug.
In addition to components, Angular also offers services. These are singleton objects that provide shared functionality across multiple components. They can be injected into any component as needed, ensuring that code isn't unnecessarily duplicated.
Services and other dependencies are managed by Angular's dependency injection system. This system creates and destroys objects as necessary, and its hierarchical nature allows different parts of your application to have different instances of a service. This feature can be very useful for testing, as it allows you to replace services with mock versions in a controlled manner.
Overall, Angular offers a robust and scalable solution for building complex web applications. Its use of TypeScript, components, and services, combined with its powerful tools for managing dependencies, make it an excellent choice for modern web development.
Let's create a simple Angular application to demonstrate some of these concepts.
- Setting up the environment: Firstly, you need to install Node.js and npm (node package manager) on your system. You can download Node.js from the official website.
- Creating a new Angular project: After setting up the environment, open your terminal and type the following command to install Angular CLI:
npm install -g @angular/cli
Then, create a new Angular project by running:
ng new my-app
This creates a new directory called 'my-app' with a pre-configured Angular application.
- Creating a component: Navigate to your new project directory and create a new component using Angular CLI:
cd my-app
ng generate component hello-world
This creates a new component named 'hello-world' with its TypeScript, HTML, and CSS files.
- Coding the component: Open the 'hello-world.component.ts' file and modify the TypeScript class:
export class HelloWorldComponent {
title = 'Hello, World!';
}
Then, open 'hello-world.component.html' and modify the HTML template:
<h1>{{ title }}</h1>
Here, {{ title }} is a binding that will be replaced by the value of the title property from the TypeScript class.
- Displaying the component: To display the 'hello-world' component, open 'app.component.html' and modify it to include the 'hello-world' component:
<app-hello-world></app-hello-world>
- Running the application: Now, start the application by running:
ng serve
Open a browser and navigate to 'http://localhost:4200/'. You should see 'Hello, World!' displayed on the page.
This simple example demonstrates the use of components and data binding in Angular. The 'hello-world' component is reusable and can be included anywhere in your application. Also note how TypeScript is used to define the behavior of the component and how HTML is used to define the view.