Book Image

Learning Angular - Third Edition

By : Aristeidis Bampakos, Pablo Deeleman
Book Image

Learning Angular - Third Edition

By: Aristeidis Bampakos, Pablo Deeleman

Overview of this book

Angular, loved by millions of web developers around the world, continues to be one of the top JavaScript frameworks thanks to its regular updates and new features that enable fast, cross-platform, and secure frontend web development. With Angular, you can achieve high performance using the latest web techniques and extensive integration with web tools and integrated development environments (IDEs). Updated to Angular 10, this third edition of the Learning Angular book covers new features and modern web development practices to address the current frontend web development landscape. If you are new to Angular, this book will give you a comprehensive introduction to help you get you up and running in no time. You'll learn how to develop apps by harnessing the power of the Angular command-line interface (CLI), write unit tests, style your apps by following the Material Design guidelines, and finally deploy them to a hosting provider. The book is especially useful for beginners to get to grips with the bare bones of the framework needed to start developing Angular apps. By the end of this book, you’ll not only be able to create Angular applications with TypeScript from scratch but also enhance your coding skills with best practices.
Table of Contents (19 chapters)
1
Section 1: Getting Started with Angular
4
Section 2: Components – the Basic Building Blocks of an Angular App
9
Section 3: User Experience and Testability
15
Section 4: Deployment and Practice

Watching state changes and being reactive

So far, we have learned how to create forms programmatically and how to specify all our fields and their validations in the code. A reactive form can listen to changes in the controls of the form when they happen and react accordingly. A suitable reaction could be to disable/enable a control, provide a visual hint, or something else according to your needs. You get the idea.

How can we make this happen? Well, a FormControl instance contains two observable properties: statusChanges and valueChanges. The first one notifies us when the status of the control changes, such as going from invalid to valid. On the other hand, the second one notifies us when the value of the control changes. Let's explore this one in more detail, using an example.

The password field in the ReactiveLoginComponent form contains a validator to check the minimum length of the value entered by the user. From an end user point of view, it would be better to display...