Start taking down the zombie horde with rapid fire web development programs. This book introduces you to JavaScript and a wide variety of beginner programming topics like variables, conditional statements, loops and functions.

An Introduction to Programming in JavaScript

JavaScript differs from other front-end web languages, such as HTML and CSS. It’s much more programmatic and uses logic and variables and functions and loops and all kinds of things—but don’t fear for your mind as though a zombie were hot on your trail. We’ll walk you through everything and get you up to speed, even if this is your first taste of JavaScript and/or of a more traditional programming language.

This book assumes a small amount of HTML/web page knowledge. If you have none, you can get what you'd need from our free book Punching Zombies: An HTML & CSS Quick Start Guide for Writers, Designers, and Beginners

Hello Human Resistance Cell

An Introduction to Programming in Javascript: Storm Zombies with Variables, Loops, Functions and More

Preface

One of the first things to understand is a concept called variables. Variables are like buckets you store things in. You can put water in a bucket or your lunch or a mannequin head or the rookie cards of the 2037 Los Angeles Zombie-Dodgers Human Resistance Cell. You can put just about anything in a bucket.

Buckets and Buckets of Zombie Guts

Some buckets can only hold one type of thing. For instance, a bucket with a hole in the bottom wouldn’t hold water or the soda from the last working soda fountain in North America, but it could be great for holding books or large rocks or the personal effects of your zombified roommate. Similarly, variables often only hold one type of thing.

Buckets of Type Z

These buckets we’ve been talking about are called variables. They’re called variables because they are…ahem…variable. You can put something in them, and, during your program, you can take that out and look at it or take it out and do something with it or take it out and put something else in. You can do that any number of times.

Variable Bucket Contents

There are several ways to output something in JavaScript. Outputting for user view is almost always the end goal, even if the results of a program do something else first. Outputting for user view is also helpful in figuring out what’s wrong in a program and how to fix it.

Undead Output

Next we’ll tackle something familiar, though it may be unpleasant for some: math. A lot of math can happen in programming and all the usual culprits are there: addition, subtraction, multiplication, and division, as well as one you may not be familiar with, modulus division.

Math after the Apocalypse

Since variables can hold almost any value, it can be difficult to keep track of what a variable/bucket is supposed to hold. The problem is exacerbated by growing complexity. But you can figure out what’s in a variable by using if-then statements. These allow you to test a condition (if) and do something based on the results (then).

Logically Challenged Zombies

The next important thing in JavaScript—and in other programming languages—is the loop. Loops are just what they sound like, they do some code again and again and again until they hit a stopping condition. There are two main types of loops (with a couple variations): the for loop and the while loop.

Getting Loopy with Zombies

Before we go further, let’s talk about variable scope—that is, where you can use a variable. When we define a bucket using var or let or const, it’s like we’re writing its name on the side. If you have a horde of buckets with names on their sides, it can take a while to find the one you want, right? So JavaScript allows you to create groups of buckets and localize the bucket names to make things easier to find and make sure there aren’t any conflicts. You can think of a group of buckets as all the buckets (variables) defined between two curly brackets. Any bucket you’ve named within that group won’t be used outside that group, but any variable declared outside that group can also be used within the group. For instance:

Zombie Sniper and Variable Scopes

There’s one more data type to discuss, though this might be better called a data structure: the array. You can think of an array as an orderly line of buckets, or a line of people with empty bowls waiting for whatever-we-got stew at your nearest human resistance cell. This line is a useful way to group everyone, and you could either go down the line and hand out stew, or you could call out names for them to come get stew, or you could send out a line of stew cooks the same size as the line of hungry people to give them stew. Whatever way you access the people in the line, you can because they’re all in one place and in an order you understand. Arrays are a line of buckets or variables. You can access all the variables in sequence using their indices (places in line), pull out a specific variable in the array (you can have string names as your indices too), or you can use a map function (we’ll get to these in the next book) to do work on all the variables at once.

An Array of Apocalyptic Outcomes

Sometimes you create a section of code that you want to use again and again—for instance, code that cures the zombie contagion or that finds the highest strength zombie in a horde.

Functional Apocalypse

You will take a two-dimensional array composed of names and a super-secret numbery biologicy thingy (NBT) and process that array using several functions. The starter HTML file/codepen will hold the array and have stubs for the functions.

Punch Those Zombies in the Array

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John is a storyteller with design and development skills. By day he designs and builds websites and mobile apps, by night he spins sci-fi stories at StoryLab ( https://storylab.us ) and counts his words carefully at https://8wordstories.com . He's a pineapple in disguise https://pineapplecomics.com and (as you know) tries to make learning web development fun by helping you kill zombies https://undead.institute . He's been lucky enough to collect a wife and five kids along with six cats, four dogs, and a small army of fish. If he remembers to wear pants, it’s been a good day.

Hello Human Resistance Cell

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