What JavaScript is and what it isn't

JavaScript, like PHP decade or so ago, got a very bad reputation as a suboptimal language, half-arsed version of Java, and any number of completely wrong attributes that were assigned to it over time. As with most languages, there is a fair deal of bad JavaScript code floating on the Internet, and I myself have probably contributed some to that when I was younger. However, this is probably not the main reason for its reputation.

JavaScript has, for very long, been the only language supported in the web browsers. If you wanted to do anything inside the browsers, you had to use it, even if you did not really like JavaScript (or at least liked some other language better). Because of this, many developers were frustrated, and attributed such frustration to the language rather than the fact that they had to use something they did not want to.

And let's not forget the fact that programmers can get quite religious when it comes to choosing tools.

JavaScript is, of course, not flawless. It has its share of warts that can annoy even the seasoned JavaScript programmers. It even has features that were meant to help programmers coming from languages such as Java orient themselves, that ended up doing the exact opposite. However, most arguments against JavaScript that you will commonly find online have nothing to do with those warts. In this module, I will try to clarify some of the misconceptions, and hopefully set the record straight for those of you that are looking to dive into this book's other modules.

JavaScript is a programming language

Have you ever encountered a person that divides programming languages into real programming languages and so-called scripting languages? If you have, have you ever been told that JavaScript is 'just a scripting language' (as opposed to a real one)? Well, they are wrong.

A scripting language is a programming language that happen to have the kind of features that make it extremely useful for scripting. Scripting is an exercise in programming with the goal of automating simple tasks that you'd have to perform manually otherwise.

For instance, let's say there's a designer that has a few hundred icons stored in individual files in, say, Adobe Illustrator, and they want all of them to be exported as .png files, it would be tedious to do all that by hand. They ask a programmer friend to write a script that automates this. Using languages like Java or C# for this type of work is clearly very expensive. It could probably be done if Illustrator had bindings for these languages, but that would not necessarily be a smart choice. Languages that are commonly used for this type of task are typically lightweight, in the sense that there is very little boilerplate and/or tooling necessary to write a fully functional program. They are, in other words, simple to code in.

We all like simple, though. Even for real programming. 'Scripting language' is not a label that you give to crippled languages that can't do anything. It's a badge of honor that says 'you can get started with this language very quickly.' Many of the so-called 'scripting languages' are perfectly usable, and in some cases even preferred, for real-life work. Starting with JavaScript, there are also Python, Ruby, PHP, Perl, and the list goes on. All of them have been used to write complex real life programs people use, love, and depend on.

JavaScript is object-oriented

JavaScript is a multi-paradigm language. Among its paradigms, you will find object-oriented (OO). Although this is true, you will find many developers that consider this to be untrue, or that JavaScript doesn't do real object-orientation.

JavaScript is, indeed, an OO programming language, but it's among the rare prototype-based OO languages (another main-stream example is Lua).

Suppose we were building houses. You would normally make a blueprint that describes what the house should look like. And then you build a house according to the blueprint. Class-based OO mimics this approach by using classes as blueprints for objects (called 'instances'). In prototype-based OO, you build a house by borrowing parts from an existing house and you add only the parts that are new and unique to your house. When we say 'borrow' we don't mean remove from the first house and bolt onto the new one. They are not cloned either. It's closer to you looking at a non-existing wall on your new house, and seeing the one from the old one magically appears before you! In fact, building a house is not even a very good analogy for prototype-based OO. After all, this is not the real world, it's a virtual world where things work the way we imagine them to.

Programmers that love the class-based OO sometimes don't like the prototype-based OO, and they complain about it loudly. Usually not even fully understanding the prototypal model, they jump to a conclusion that something is wrong with it and/or that it's incomplete.

There are also valid arguments against prototype-based OO, such as difficulty in ensuring correctness of your programs at compile time, and poor performance. While these stand, in practice, it is rarely a critical flaw.

Prototype-based OO is neither wrong or incomplete. It is what it is, and it's not class-based. If you want to do OO programming in JavaScript, there is very little choice but to embrace prototypes (or use TypeScript).

JavaScript is functional

JavaScript was originally intended to be a functional programming language. I don't mean 'functional' as in 'working'. I mean a language that supports the functional programming paradigm.

There are programmers out there that say this is impossible, but what they really mean is that JavaScript is not a pure functional programming language.

In pure functional programming languages, you cannot have mutation and side-effects. Mutation means reassigning variable values. In JavaScript, it is possible to reassign them, so it's impure. JavaScript also embraces side-effects. It's not only impure, but outright filthy!

However, it is possible to write programs in functional style, with or without helpers and checkers that ensure mutations and side-effects are kept to bare minimum, and this tends to be really successful because of what JavaScript was intended to be.

JavaScript is also a good language to start learning functional programming at work, because it allows you to fall back on other paradigms and stay productive while you convert your code to functional style. In other words it's not an either-or choice.

Due to steadily growing interest in this paradigm, JavaScript is only going to get better and better at it, too.

JavaScript is a platform

JavaScript is not only a programming language, but also a platform. There are many languages that target JavaScript as the runtime environment. Starting with various variants of JavaScript, including ECMAScript 6 that is used in this book, to TypeScript mentioned earlier, to CoffeeScript, LiveScript, Elm, PureScript, and even F#, and C/C++!

Some of these languages simply fix a few warts authors found in JavaScript or bring in features that are not (yet) supported, others are completely different languages with no semblance to JavaScript, created to solve different problems than those JavaScript was originally intended for, and some are different main-stream languages on their own, where the main goal of compiling to JavaScript is code reuse across platforms. This ecosystem is becoming larger and larger, and nowadays it's increasingly rare to write JavaScript programs that are intended to be executed as is.

Even though JavaScript originated in browsers, it is now capable of running on servers and desktops, and even embedded devices! The incentive to target JavaScript as a platform rather than a language is clearly there.

If you are wondering whether you should even bother learning JavaScript, I don't have a clear answer for you. These are very exciting times, and there are so many options. JavaScript, the language, is still evolving, and there is a large volume of know-how and code around it. It's quite obviously not going away any time soon. That much is for sure.

You can make money programming in JavaScript

I doubt anyone would dispute this, but let me throw it in just in case. Whatever anyone says about any of the above, you can make a handsome living programming in JavaScript, and JavaScript alone. You would be missing out on so many cool languages, but the point is that JavaScript programmers are sought-after commodity and you couldn't go wrong making it your first and/or primary weapon of choice.

In conclusion

JavaScript is a pretty awesome programming language that supports many exciting ways to express your programs, from simplest scripts to complex real-life systems, and allows you to make a decent living while doing so. Try to not get mislead by what people who cannot accept JavaScript for what it is say, and explore the awesome projects created by those who could not accept it and decided do something about it.

Also remember that JavaScript is not the best language out there, and certainly not the only one. It's not an end-all-be-all language that you can use in every situation. You should continue to learn new languages throughout your programming life and enrich yourself with new perspectives. Even if you, like me, keep coming to JavaScript, you will find that your programming is always permanently expanded by the experiences you have in other languages.