Why JavaScript?

When we were putting this course together, we decided we didn't want to be conceptual, we wanted to get hands on, and we talked a lot about what would be a good language to do this with. We wanted a language that was friendly for beginners but not just a beginner's language. It needed to be real. It needed to be popular and it needed to be relevant. Overall it needs to be a language that was good to explain these concepts. Now there are a lot of languages that fit the bill here, but very importantly we also wanted one that you could get started with without installing anything on any platform and that narrows the list down quite a bit.

So we decided to go with JavaScript. It's not the most powerful or the most flexible language out there, but it's certainly popular and it's certainly relevant, and it's a great language for exploring these concepts. So even if you had some other language in mind, JavaScript is a very practical language to know. But JavaScript is a language that works with and manipulates web pages. It was invented for that reason. And that does mean that JavaScript is specialized and intentionally limited.

We wouldn't use JavaScript to write say desktop applications, the way that I might with C++ or Java or C# or Objective-C. And despite the name Java and JavaScript are totally different languages and are not related in any meaningful way. So programs that I write in these languages would run directly on the operating system. JavaScript wouldn't. While JavaScript is a programming language, you'll also here refer to as a scripting language.

Now this is a description you hear not surprisingly for any language with script at the end like ActionScript or AppleScript or VBScript. Scripting languages are more limited programming languages that are embedded inside another program. So ActionScript for example is the programming language that we use inside Flash. VBScript can be used inside Microsoft Office applications, and similarly JavaScript also only works inside another application, the web browser.

whether your browser is Internet Explorer or Safari or Firefox or Chrome or Opera, they all have a JavaScript engine, a JavaScript interpreter inside of them. Scripting languages in general aren't more limited than these general purpose programming languages, but they are often easier to pick up and they're very good at what they do. So JavaScript like most scripting languages is an interpreted language. We do not have to manually compile it to machine code.

That will automatically be done by the web browser when we try and run our JavaScript. So the operating system runs the web browser and the web browser runs our JavaScript. JavaScript very importantly is a case-sensitive language. For those of you new to programming I can't get over how important that it is. Let me show you two example lines of JavaScript here. Now don't worry right now about what they do, but just know that one of these is right and one of these is wrong. What we actually have here is one is using the word Id with a lowercase d and the other has an uppercase D.

This is the level of case sensitivity that we have to be aware of in any language that is case sensitive and most of them are. Even if you have a language that isn't, you probably want to make a habit of paying very close attention to it, because one of these would work and one of these wouldn't. So here is some JavaScript. This is what it looks like in general. Again, don't worry right now about what this is doing. But when we see any programming language with a lot of these curly braces being used, when we see statements that all seem to end in a semicolon, and a few of the other things we'll be exploring shortly about this, this is a clue that this language is influenced by the C programming language.

C has been around since the early 70s and shapes the look of many of the most popular languages today. Some even share the name C++, C#, Objective-C ,and some don't. Java is a C style language, as is ActionScript, as is JavaScript. And knowing a C style language makes it easier to jump into any of these other languages. So JavaScript is a C-based interpreted case-sensitive language. It's highly relevant and it's pretty friendly for beginners.

So let's see how to create our first program in JavaScript.