Mastering TypeScript 3 - Third Edition

Angular Reactive forms

Reactive forms have been introduced into the Angular framework to provide the ability to create forms that can change dynamically. In other words, we can modify the validity checks of a particular form control on the fly, or mark some properties as required or disabled programmatically. As an example of this, some form controls may change the minimum length of input depending on what a user has selected in another control. Or, some form inputs may or may not be required, depending on what the user has selected on another part of a form. By moving the declaration of these forms into the component, we can modify it using standard code, and can exercise greater control over our forms.

In order to use Reactive forms, we ...