What are reactive forms in Angular?

Reactive Forms is a model-driven approach to handling form inputs in Angular, a popular web application framework. This approach emphasizes immutability and predictability, giving developers more control over the form's behavior and validation logic.

In Reactive Forms, the form's structure and logic are defined in the component class using instances of classes like FormControl, FormGroup, and FormArray. This contrasts with Angular's Template-Driven Forms, where much of the form's definition is embedded directly in the HTML template.

A key benefit of Reactive Forms is that they provide a straightforward way to unit test the form's logic, since that logic is contained within the component class and can be tested without interacting with the template. Reactive Forms also make it easier to dynamically change the form's structure or behavior in response to changing conditions, such as user input. Apart from it by obtaining Angular Course, you can advance your career in Angular. With this course, you can demonstrate your expertise in applications using React concepts such as Angular Modules, Components, Databinding, Angular Forms, Angular Directives and Pipes, Services and Dependency Injection (DI), many more fundamental concepts, and many more.

Here's a basic outline of how Reactive Forms might be used in an Angular application:

1. Importing the ReactiveFormsModule: To use Reactive Forms, the ReactiveFormsModule must be imported into the Angular module that contains the component.

2. Creating Form Controls: Within the component class, form controls are created using the FormControl class, and groups of controls are created using the FormGroup class. These classes provide methods for setting, retrieving, and validating the form's data.

3. Binding to the Template: In the HTML template, the [formGroup] directive is used to bind the form group to a <form> element, and the formControlName directive is used to bind individual form controls to input elements.

4. Handling Changes and Validation: Reactive Forms provide observables that can be used to react to changes in the form's value or validity status. Custom validation logic can be implemented using the Validators class, or custom validation functions.

5. Submitting the Form: Typically, the component class would define a method to be called when the form is submitted, allowing the collected data to be sent to a server or otherwise processed.

Reactive Forms provide a powerful, flexible way to gather and validate user input in Angular applications. They allow for a clean separation between the template and the underlying logic, facilitate testing, and provide a suite of tools for common form-related tasks, making them a popular choice for complex forms and dynamic user interfaces.