This book is for anybody who is absolutely new to JavaScript and is willing to learn this technology. This book can also be used by people who are familiar with old JavaScript and want to level up their knowledge to the latest standard and use techniques. For more advanced users, this book can be used to brush up concepts such as modularity, web workers, and shared memory.

Chapter 1, Getting Started with ECMAScript, discusses what ECMAScript really is and why we call it ECMAScript and not JavaScript. It also discusses how to create variables, perform basic operations, and provides new ways to do those operations in ES8.

Chapter 2, Knowing Your Library, demonstrates all the functions you need to know as a beginner and intermediate JavaScript developer to work smoothly on various kinds of projects. The functions taught in this chapter are universal and generic functions, which you'll be able to understand and apply anywhere they're necessary for your code.

Chapter 3, Using Iterators, covers how to iterate over iteratable things in JavaScript the proper way. We discuss Symbol, a new native JavaScript type, what it is, and why we need it. We also discuss the tail call optimization technique, which is implemented by browsers to speed up the code.

Chapter 4, Asynchronous Programming, explores modern ways to implement asynchronous programming and compares it with the not-so-beautiful past approaches, which included callback hell. It'll teach you about implementing asynchronous programming in a synchronous way.

Chapter 5, Modular Programming, discusses modularizing your JavaScript code into different files so that it is easy to reuse and debug individual modules. We start with primitive and third-party solutions available earlier and then cover the native support browsers are bringing to the world.

Chapter 6, Implementing the Reflect API, demonstrates information about the Reflect API provided in JavaScript, which basically helps to manipulate the properties and methods of the objects.

Chapter 7, Proxies, introduces a new implementation in JavaScript, that is, proxies over objects. It has a number of advantages, such as hiding private properties, setting default values for object properties and methods, and making awesome custom features. Such as Python-like array slicing for JavaScript.

Chapter 8, Classes, explores classes, how they're implemented, inheritance in classes, and how finally classes is just a syntatic sugar over the function implementation only. This is important because classes make the code more readable and understandable to people coming from an OOP background.

Chapter 9, JavaScript on the Web, explores the basics of using JavaScript on websites, some popular APIs exposed by browser on the web to the developers, and how JavaScript can be used to interact with the DOM to manipulate things on a web page.

Chapter 10, Storage APIs in JavaScript, explores the available storage APIs in web browsers and shows how to make use of them to store data locally on the user's computer.

Chapter 11, Web and Service Workers, discusses web workers available in HTML5, service workers for progressive web apps, and shows how to use these workers efficiently to distribute loads of tasks.

Chapter 12, Shared Memory and Atomics, teaches us how to harness a multithreaded environment provided by web workers using shared memory to allow blazingly fast access to memory by the web workers through SharedArrayBuffer. It covers some of the common problems related to threads sharing the same data, and also provides solutions to those problems. 

Although it's not strictly required, it'll be great if you know a little about HTML/CSS and a little about how to create basic web pages using it.

You should be familiar with a modern browser (Chrome or Firefox is preferred) on a desktop/laptop.

To get the most out of this book, don't just read the book alone; keep other study sources open and implement as many of the demo and example codes as you can.

let myCounter = counter(); // returns a function (with count = 1)
myCounter(); // now returns 2
myCounter(); // now returns 3

var ob1 = {
   prop1 : 1,
    prop2 : {
        prop2_1 : 2 
    }
};
Object.freeze( ob1 );

Feedback from our readers is always welcome.

General feedback: Email [email protected] and mention the book title in the subject of your message. If you have questions about any aspect of this book, please email us at [email protected].

Errata: Although we have taken every care to ensure the accuracy of our content, mistakes do happen. If you have found a mistake in this book, we would be grateful if you would report this to us. Please visit www.packtpub.com/submit-errata, selecting your book, clicking on the Errata Submission Form link, and entering the details.

Piracy: If you come across any illegal copies of our works in any form on the Internet, we would be grateful if you would provide us with the location address or website name. Please contact us at [email protected] with a link to the material.

If you are interested in becoming an author: If there is a topic that you have expertise in and you are interested in either writing or contributing to a book, please visit authors.packtpub.com.