Angular Components
Definition: Angular components are the building blocks of an Angular application. They control a portion of the user interface and manage the logic for displaying data and handling user interactions.
Structure:
Component Class: Contains the logic and data for the component. It is defined using a TypeScript class.
Component Decorator: Uses the @Component decorator to provide metadata about the component, such as its selector, template URL, and style URLs.
Metadata Properties:
selector: The custom HTML tag that represents the component.
templateUrl: The path to the component’s HTML template.
styleUrls: The paths to the component’s CSS styles.
Example
@Component({
selector: ‘app-user-profile’,
templateUrl: ‘./user-profile.component.html’,
styleUrls: [‘./user-profile.component.css’]
})
export class UserProfileComponent {
user = {
name: ‘John Doe’,
email: ‘john.doe@example.com’
};
updateUser() {
// Logic to update user information
}
}
Angular Templates
Definition: Templates in Angular define the view or the UI of a component. They are written in HTML and can include Angular-specific syntax for binding data and handling user events.
Role:
Data Binding: Connects the component’s data to the HTML. There are four types of data binding.
Interpolation: Display component properties in the template ({{ property }}).
Property Binding: Bind HTML element properties to component properties ([property]=”expression”).
Event Binding: Listen for and respond to user events ((event)=”expression”).
Two-Way Binding: Combine property and event binding for form elements ([(ngModel)]=”property”).
Directives: Angular templates can use directives to manipulate the DOM. There are structural directives like *ngIf and *ngFor for conditional rendering and iteration.
Example: html
<h2>{{ user.name }}</h2>
<p>Email: {{ user.email }}</p>
<button (click)=”updateUser()”>Update Profile</button>
</div>
Role in Building Angular Applications
Modularity: Components allow for modular development, making it easy to break down the application into manageable, reusable pieces.
Separation of Concerns: By separating the logic (component class) from the presentation (template), Angular promotes clean and maintainable code.
Reusability: Components can be reused throughout the application, reducing duplication and simplifying maintenance.
Testability: Components, being self-contained units, are easier to test individually.
Together, components and templates form the core of Angular applications, enabling developers to create dynamic, interactive, and maintainable user interfaces.
