Book Image

Angular Services

By : Sohail Salehi
Book Image

Angular Services

By: Sohail Salehi

Overview of this book

A primary concern with modern day applications is that they need to be dynamic, and for that, data access from the server side, data authentication, and security are very important. Angular leverages its services to create such state-of-the-art dynamic applications. This book will help you create and design customized services, integrate them into your applications, import third-party plugins, and make your apps perform better and faster. This book starts with a basic rundown on how you can create your own Angular development environment compatible with v2 and v4. You will then use Bootstrap and Angular UI components to create pages. You will also understand how to use controllers to collect data and populate them into NG UIs. Later, you will then create a rating service to evaluate entries and assign a score to them. Next, you will create "cron jobs" in NG. We will then create a crawler service to find all relevant resources regarding a selected headline and generate reports on it. Finally, you will create a service to manage accuracy and provide feedback about troubled areas in the app created. This book is up to date for the 2.4 release and is compatible with the 4.0 release as well, and it does not have any code based on the beta or release candidates.
Table of Contents (15 chapters)
Angular Services
About the Author
About the Reviewer
Customer Feedback

Event binding

Sometimes we need to direct the data flow from the template to the component. In other words, we need to listen for an event in a DOM element and act upon it inside the Component class. That means we need to bind a method to an event--that is why it is called event binding.

The event binding syntax is very easy. On the left side, we mention the name of the event we are interested in, and on the right side we write the method name--in the component class--which this event will be bound to:

(event) = "onEvent(parameters)" 

To see how it works, let's listen for checked headlines and show them in the console. Later in this chapter, we will see how to persist the selected headlines in a database for future reference. But for now logging them in the browser's console will be enough.

  1. First we need to listen for change events on the checkbox elements, so modify the <input> tag as follows:

            # app/collector/collector.html 
            # ... 
            <li *ngFor="let headline...