JavaScript is no longer to be feared or loathed - the world's most popular and ubiquitous language has evolved into a respectable language. Whether you're writing frontend applications or server side code, the phenomenal features from ES6 and beyond - like the rest operator, generators, destructuring, object literals, arrow functions, modern classes, promises, async, and metaprogramming capabilities - will get you excited and eager to program with JavaScript. You've found the right book to get started quickly and dive deep into the essence of modern JavaScript. Learn practical tips to apply the elegant parts of the language and the gotchas to avoid.
 

JavaScript is a black swan that no one, including the author of the language, thought would become a popular and ubiquitous language. Not long ago, it was the most hated and feared language you could use to program the web. JavaScript ES6 and beyond has gone through a significant makeover. Troublesome features have been replaced with better, elegant, more reliable alternatives. This book includes many practical examples and exercises to help you learn in depth. It will not bore you with idiosyncrasies and arcane details intended for bad interview questions. Instead, it takes you into key features that you can readily use in your day-to-day projects.
 

Whether you program the frontend or the server side, you can now write concise, elegant, and expressive JavaScript with newer features like default parameters, template literals, rest and spread operators, destructuring, arrow functions, and generators. Take it up a notch with features like infinite series, promises, async, and metaprogramming to create flexible, powerful, and extensible libraries. While the evolved features of the language will draw you in, the hundreds of examples in this book will pin the concepts down, for you to use on your projects. Take command of modern JavaScript and unlock your potential to create powerful applications.

What You Need:

To try out the examples in the book you will need a computer with Node.js, a text editor, and a browser like Chrome installed in it.

This book is for programmers, full-stack developers, lead developers, software architects, technical managers, or just about anyone who dives into code and is interested in learning and applying modern JavaScript. If you feared JavaScript or if the language annoyed you in the past, this book will show how the language has beautifully evolved in ECMAScript 2015 (ES6), 2016 (ES7), and 2017 (ES8) and how it is now highly approachable. You can make use of these features to program the front or the back end using JavaScript.

This book assumes the reader is familiar with basics of programming—it does not teach the fundamentals of programming. Some prior knowledge of JavaScript will be helpful. Programmers who are familiar with languages like Java, C#, and Python but who are not familiar with JavaScript should be able to pick up the concepts presented fairly quickly.

If you’re already familiar with the materials presented in this book, you may use this book to help train your developers.
 

What’s in This Book?

Before we dig into the newer features of JavaScript, we’ll quickly visit some old problem areas in Chapter 1, ​JavaScript Gotchas​. You’ll learn about things to avoid and the safe alternatives to some nefarious features.

Chapter 2, ​Variables and Constants​ will encourage you to replace var with let or const and why you should prefer const where possible.

JavaScript has always had support for flexible parameters, but it was not intuitive and was also error prone. Chapter 3, ​Working with Function Arguments​ will show how the newer features of JavaScript make working with parameters safe, expressive, and pleasant.

The enhanced for loop of modern JavaScript is the antidote for the boredom of the common loops. We discuss different ways to loop, along with the generators and how to create infinite sequences, in Chapter 4, ​Iterators and Symbols​.

The lexical scoping semantics of anonymous functions is inconsistent and confusing, to say the least. Arrow functions don’t have majority of the problems that are inherent in anonymous functions. But arrow functions come with some limitations as well, as we’ll see in Chapter 5. We’ll see how arrow functions make it easy to create functional style code.

Hands down, one of the most exciting features of JavaScript is destructuring. In Chapter 6, ​Literals and Destructuring​ we’ll unleash the power of destructuring along with features like template literals and enhanced object literals.

JavaScript has supported classes for a long time, but without the class keyword. Sadly, that created problems. The newer class-related syntax in JavaScript makes writing object-oriented code much simpler, as we’ll see in Chapter 7, ​Working with Classes​.

Unlike many other languages that support class-based inheritance, JavaScript has prototypal inheritance. Even though this feature is highly powerful and flexible, using it has been hard in the past—with the syntax confusing and error prone. As we’ll see in Chapter 8, ​Using Inheritance​, it’s now much easier, and safer, to use inheritance.

In Chapter 9, ​Using Modules​, you’ll learn to work with multiple JavaScript files and the rules of module import and export.

Asynchronous programming is a way of life in JavaScript, and you need a fairly good knowledge of how promises work to master that. Chapter 10, ​Keeping Your Promises​, has you covered.

There’s something magical about metaprogramming—the ability to create programs that can create programs. In Chapter 11, ​Exploring Metaprogramming​, we’ll explore one type of metaprogramming—injection.

Then, in Chapter 12, ​Deep Dive into Metaprogramming​, we dig into another type of metaprogramming—synthesis—and how to create highly dynamic code.

Appendix 1, ​Answers to Exercises​ has solutions for exercises at the end of each chapter, for you to compare notes with the solutions you create.

Finally, for your convenience, the URLs that are scattered throughout this book are gathered in one place in Appendix 2, ​Web Resources​.

About the Author

Dr. Venkat Subramaniam is an award-winning author, founder of Agile Developer, Inc., and an instructional professor at the University of Houston. He has trained and mentored thousands of software developers in the US, Canada, Europe, and Asia, and is a regularly invited speaker at several international conferences. He's the (co)author of multiple books, including the 2007 Jolt Productivity award winning book Practices of an Agile Developer.