Chapter 19. Introduction to JavaScript
by Mat Marquis
In this chapter, I’m going to introduce you to JavaScript. Now, it’s possible you’ve just recoiled a little bit, and I understand. We’re into full-blown “programming language” territory now, and that can be a little intimidating. I promise, it’s not so bad!
We’ll start by going over what JavaScript is—and what it isn’t—and discuss some of the ways it is used. The majority of the chapter is made up of an introduction to JavaScript syntax—variables, functions, operators, loops, stuff like that. Will you be coding by the end of the chapter? Probably not. But you will have a good head start toward understanding what’s going on in a script when you see one. I’ll finish up with a look at some of the ways you can manipulate the browser window and tie scripts to user actions such as clicking or submitting a form.
What Is JavaScript?
If you’ve made it this far in the book, you no doubt already know that JavaScript is the programming language that adds interactivity and custom behaviors to our sites. It is a client-side scripting language, which means it runs on the user’s machine and not on the server, as other web programming languages such as PHP and Ruby do. That means JavaScript (and the way we use it) is reliant on the browser’s capabilities and settings. It may not even be available at all, either because the user has chosen to turn ...
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