Book Image

Essential Angular

By : Victor Savkin, Jeff Cross
Book Image

Essential Angular

By: Victor Savkin, Jeff Cross

Overview of this book

Essential Angular is a concise, complete overview of the key aspects of Angular, written by two Angular core contributors. The book covers the framework's mental model, its API, and the design principles behind it. This book is fully up to date with the latest release of Angular. Essential Angular gives you a strong foundation in the core Angular technology. It will help you put all the concepts into the right places so you will have a good understanding of why the framework is the way it is. Read this book after you have toyed around with the framework, but before you embark on writing your first serious Angular application. This book covers concepts such as the differences between Just-In-Time (JIT) and Ahead-Of-Time (AOT) compilation in Angular, alongside NgModules, components and directives. It also goes into detail on Dependency Injection and Change Detection: essential skills for Angular developers to master. The book finishes with a look at testing, and how to integrate different testing methodologies in your Angular code.
Table of Contents (11 chapters)

Host element

To turn an Angular component into something rendered in the DOM you have to associate an Angular component with a DOM element. We call such elements host elements.

A component can interact with its host DOM element in the following ways:

  • It can listen to its events
  • It can update its properties
  • It can invoke methods on it

The component, for instance, listens to the input event using hostListeners, trims the value, and then stores it in a field. Angular will sync up the stored value with the DOM.

selector: '[trimmed-input]'
class TrimmedInput {
@HostBinding() value: string;

@HostListener("input", "$")
onChange(updatedValue: string) {
this.value = updatedValue.trim();

Note, I don't actually interact with the DOM directly. Angular aims to provide a higher-level API, so the native platform, the DOM, will just reflect the state...