Book Image

Learning Angular - Fourth Edition

By : Aristeidis Bampakos, Pablo Deeleman
5 (1)
Book Image

Learning Angular - Fourth Edition

5 (1)
By: Aristeidis Bampakos, Pablo Deeleman

Overview of this book

As Angular continues to reign as one of the top JavaScript frameworks, more developers are seeking out the best way to get started with this extraordinarily flexible and secure framework. Learning Angular, now in its fourth edition, will show you how you can use it to achieve cross-platform high performance with the latest web techniques, extensive integration with modern web standards, and integrated development environments (IDEs). The book is especially useful for those new to Angular and will help you to get to grips with the bare bones of the framework to start developing Angular apps. 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. Updated for Angular 15, this new edition covers lots of new features and tutorials that address the current frontend web development challenges. You’ll find a new dedicated chapter on observables and RxJS, more on error handling and debugging in Angular, and new real-life examples. 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 (17 chapters)
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Unsubscribing from observables

When we subscribe to an observable, we create an observer that listens for changes in a data stream. The observer watches the stream continuously while the subscription remains active. When a subscription is active, it reserves memory in the browser and consumes certain resources. If we do not tell the observer to unsubscribe at some point and clean up any resources, the subscription to the observable will possibly lead to a memory leak.

An observer usually needs to unsubscribe when the Angular component that has created the subscription needs to be destroyed.

Some of the most well-known techniques to use when we are concerned with unsubscribing from observables are the following:

  • Unsubscribe from an observable manually
  • Use the async pipe in a component template

Let's see both techniques in action in the following sections.

Destroying a component

A component has life cycle events we can hook on and perform custom logic, as...