WRITING COMPUTER CODE

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John Wiley & Sons, Inc.
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Copyright © 2016 by John Wiley & Sons, Inc., Hoboken, New Jersey

Published simultaneously in Canada

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Library of Congress Control Number: 2016941390
ISBN 978-1-119-17730-2 (pbk); ISBN 978-1-119-17732-6 (ebk); ISBN 978-1-119-17733-3 (ebk)

ABOUT THIS BOOK

In this book, you’ll learn to use HTML5, CSS3, and JavaScript to create programs for computers. More people have used these three computer-coding languages than any other coding language that’s ever been invented. In fact, every single website that you visit makes use of these three languages. That’s why we think you’ve made a great decision by beginning your journey into the world of coding by picking up Writing Computer Code.

Computer code is fun and easy to learn. With some determination and a lot of imagination, you’ll be creating your very own computer programs in no time!

Just as the only way to become a great athlete or musician is to practice, practice, practice, the only way to become a computer programmer is to write code, write code, write code!

This book is put together as a series of projects with steps for constructing each project from start to finish. The projects also build upon one another, so that by the end of the book you’ll have an animated robot that you can control with your mouse and continue to modify and improve long after you finish all the projects.

Here’s what you need to do the projects in this book:

• A computer running the Windows, Mac OS X, or Linux operating system
• A web browser, like Chrome, Firefox, or Safari
• An Internet connection

As you work through each project, keep in mind the following:

• Code and web addresses are in monofont. If you’re reading this as an ebook, you can click web addresses, like www.dummies.com, to visit that website.
• When you’re getting started, the best way to learn is to see how other people do it. For this reason, we’ve included pictures for every important step in the book, and all our examples are online at http://jsfiddle.net/user/watzthis/fiddles. If you want to check your work, or just copy ours, be sure to look at both of these.
• Every project wraps up with a last look at the project’s big ideas in coding. The big ideas consist of codes and concepts you’ll find useful for future projects.
• Coding isn’t that hard, but it does come with a lot of technical details. If you don’t feel like reading all the explanations, just skip ahead to the next code example and try it out.

ABOUT YOU

We already know that you’re ready and willing to code. Because you’re reading this, we know you’re fully qualified and able to get started right away. We don’t make many assumptions, but here are the things we wanted to mention upfront:

• You should be comfortable with using a web browser to visit websites, and with typing on a keyboard. The projects in this book won’t likely work on a phone or tablet without a keyboard.
• You’re comfortable with very basic math. We’re talking about addition, subtraction, multiplication, and division. We don’t require anything very advanced at all, but basic math is an important part of programming.
• You have the patience and dedication to stick with it and troubleshoot bugs. We guarantee that programming can be a lot of fun, but we also guarantee that it can be frustrating when you have to track down the one typo or missed command that is making your whole program not work. Stick with it!

That’s really all there is to it. If you get stuck, keep in mind that many problems in writing computer code happen simply because of spelling errors or words that you type that a computer can’t understand. Proceed slowly and carefully, and you’ll do great!

ABOUT THE ICONS

As you read through the projects in this book, you’ll see a few icons. The icons point out different things:

Watch out! The Warning icon marks important information that you can use to avoid common pitfalls when coding.

The Remember icon marks concepts you’ve encountered before and should keep in mind while coding.

The Tip icon marks advice and shortcuts that will help you create code and graphics quickly and easily.

The Fun with Code icon describes how the coding you’re doing relates to the bigger picture of computer programming.

The Fun with Math icon describes the everyday math you use while coding computer programs. Finally, you see how that stuff really is used!

THE FIRST STEP

Once you take your first steps down the road of writing code, the world of computers will open up to you and you’ll be able to use your computer to do some pretty amazing things. You’ll also join the community of millions of programmers around the world as we shape the web and the future! Congratulations on taking the first step!