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)

Immutability and Side Effects

In a pure function context, the mutation of variables is considered a side effect and therefore a function where the mutation occurs, especially of variables that live beyond the execution of the function, is not pure.

Immutability in JavaScript is hard to enforce but the language gives us good primitives to write in an immutable style. This style leans heavily on operators and functions that create a copy of data instead of mutating in place.

It is possible to write entire sections of applications without using side effects. Any data manipulation is possible without side effects. Most applications, however, need to load the data so that it is displayed from somewhere and possibly save some of the data somewhere as well. These are side effects that need to be managed.

A Look at Redux Action Creators

Action creators create Redux actions. They're useful to abstract the constants and centralize what actions the Redux store supports.