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)


In the previous chapter, we learned how we can use arrays and objects and their helper functions. In this chapter, we will learn more about how JavaScript runs and how we can handle time-consuming operations.

When working on large-scale projects with JavaScript, often, we must deal with network requests, disk IO, and data processing. Many of these operations take time to complete, and for beginners who have just started using JavaScript, it is very difficult to understand how to retrieve the results of these time-consuming operations. This is because, unlike other languages, JavaScript has a special way of handling these operations. When coding programs, we are used to linear thinking; that is, the program executes line by line and only breaks that flow when we have loops or branches. For example, if you wanted to make a simple network request in Java, you would have to do something similar to what's shown in the following code:

import java...