Cay S. Horstmann - Modern Javascript for the Impatient

Experienced programmers familiar with languages such as Java, C#, C, and C++ often find themselves in a position where they need to work with JavaScript. User interfaces are increasingly web-based, and JavaScript is the lingua franca of the web browser. The Electron framework extends this capability to rich client applications, and there are multiple solutions for producing mobile JavaScript apps. Increasingly, JavaScript is used on the server side.

Many years ago, JavaScript was conceived as a language for programming in the small, with a feature set that can be confusing and error-prone for larger programs. However, current standardization efforts and tool offerings go far beyond those humble beginnings.

Unfortunately, it is difficult to learn modern JavaScript without getting bogged down with obsolete JavaScript. Most books, courses, and blog posts are focused on transitioning from older JavaScript versions, which is not helpful for migrants from other languages.

That is the issue that this book addresses. I assume that you, the reader, are a competent programmer who understands branches and loops, functions, data structures, and the basics of object-oriented programming. I explain how to be productive with modern JavaScript, with only parenthetical remarks about obsolete features. You will learn how to put modern JavaScript to use, while avoiding pitfalls from the past.

JavaScript may not be perfect, but it has shown itself to be well-suited for user interface programming and many server-side tasks. As Jeff Atwood said presciently: Any application that can be written in JavaScript, will eventually be written in JavaScript.

Work through this book, and learn how to produce the next version of your application in modern JavaScript!

If you avoid a small number of classic features of JavaScript, you can greatly reduce the mental load of learning and using the language. These rules probably wont make sense to you right now, but I list them here for your future reference, and to reassure you that they are few in number.

1. Declare variables with let or const, not var.

2. Use strict mode.

3. Know your types and avoid automatic type conversion.

4. Understand prototypes, but use modern syntax for classes, constructors, and methods.

5. Dont use this outside constructors or methods.

And a meta-rule: Avoid the Watthose snippets of confusing JavaScript code followed by a sarcastic Wat?! Some people find delight in demonstrating the supposed awfulness of JavaScript by dissecting obscure code. I have never learned anything useful from going down that rabbit hole. For example, what is the benefit of knowing that 2 * ['21'] is 42 but 2 + ['40'] is not, if the golden rule #3 tells you not to mess with type conversions? In general, when I run into a confusing situation, I ask myself how to avoid it, not how to explain its gory but useless details.

When I wrote the book, I was trying to put information where you can find it when you need it. But thats not necessarily the right place when you read the book for the first time. To help you customize your learning path, I tag each chapter with an icon that indicates its basic level. Sections that are more advanced than the chapter default get their own icons. You should absolutely skip those sections until you are ready for them.

Here are the icons:

The impatient rabbit denotes a basic topic that even the most impatient reader should not skip.

Alice indicates an intermediate topic that most programmers want to understand, but perhaps not on first reading.