Angular Tutorial part 3 - Directive and Custom Directive

Angular directives are one of the core features of the Angular framework. They allow developers to extend the HTML language with new elements and attributes that can be used to manipulate the Document Object Model (DOM). Directives can be used to add custom behavior to an HTML element, such as adding new styling, handling events, or changing the structure of the page.

There are several types of directives in Angular, including structural directives and attribute directives. Structural directives are used to manipulate the structure of the DOM, such as adding or removing elements from the page. Attribute directives are used to manipulate the appearance or behavior of an HTML element.

One of the most powerful features of Angular is the ability to create custom directives. Custom directives allow developers to create their own elements and attributes that can be used in an Angular application. Custom directives are typically used to encapsulate complex logic or behavior, such as adding animations, handling user events, or working with external data.

To create a custom directive in Angular, you use the @Directive decorator to define a new class. This class will contain the logic and behavior of the directive. You can then use the selector property of the @Directive decorator to specify the name of the directive that you will use in your HTML.

In addition to the @Directive decorator, a custom directive may also need to use other Angular features, such as services and dependency injection, to work with data or perform other tasks. This allows you to encapsulate complex logic in a custom directive and reuse it throughout your application.

One common use case for custom directives is adding custom animations to an Angular application. You can use a custom directive to animate the appearance or disappearance of elements on the page, such as showing or hiding a menu. This can be done using Angular's animation library and the @HostBinding and @HostListener decorators.

Another common use case for custom directives is adding custom event handling to an Angular application. You can use a custom directive to handle events, such as clicking a button, and perform specific actions in response. This can be done using the @Output and EventEmitter classes in Angular.

Overall, custom directives are a powerful feature of Angular that allow developers to extend the HTML language and add custom behavior and functionality to their applications. Whether you're adding custom animations, handling events, or working with external data, custom directives provide a way to encapsulate complex logic and reuse it throughout your application.

In conclusion, Angular directives are a key part of the Angular framework, and the ability to create custom directives allows developers to extend the HTML language and add custom behavior and functionality to their applications. Custom directives provide a way to encapsulate complex logic and reuse it throughout your application, making it easier to build complex and dynamic web applications with Angular.