Book Image

Professional JavaScript

By : Hugo Di Francesco, Siyuan Gao, Vinicius Isola, Philip Kirkbride
Book Image

Professional JavaScript

By: Hugo Di Francesco, Siyuan Gao, Vinicius Isola, Philip Kirkbride

Overview of this book

In depth knowledge of JavaScript makes it easier to learn a variety of other frameworks, including React, Angular, and related tools and libraries. This book is designed to help you cover the core JavaScript concepts you need to build modern applications. You'll start by learning how to represent an HTML document in the Document Object Model (DOM). Then, you'll combine your knowledge of the DOM and Node.js to create a web scraper for practical situations. As you read through further lessons, you'll create a Node.js-based RESTful API using the Express library for Node.js. You'll also understand how modular designs can be used for better reusability and collaboration with multiple developers on a single project. Later lessons will guide you through building unit tests, which ensure that the core functionality of your program is not affected over time. The book will also demonstrate how constructors, async/await, and events can load your applications quickly and efficiently. Finally, you'll gain useful insights into functional programming concepts such as immutability, pure functions, and higher-order functions. By the end of this book, you'll have the skills you need to tackle any real-world JavaScript development problem using a modern JavaScript approach, both for the client and server sides.
Table of Contents (12 chapters)


Our previous approach – that is, dealing with component communication – was direct and really static. We need to store the component reference we want to communicate with and write very component-specific code when we want to send a message to it. In JavaScript, there is a new way of communicating, and it's called eventing.

Let's consider this example; the light that's passed to you by your friend is a way for you to receive events from your friend. In JavaScript, we can have objects that have the ability to emit events. By emitting events, we can create a new way of communicating between our objects. This is also called the observer pattern. The following diagram depicts the observer pattern:

Figure 9.2: The observer pattern

In this pattern, instead of calling specific methods in our component, the component that wants to initiate communication will simply emit an event. We can have multiple observers that observe events...