A Beginner's Guide to BitBurner and JavaScript

Welcome to my guide on BitBurner where we go from zero knowledge on JavaScript (Or TypeScript, if you so choose) to a fully fledged script to hack the best server!

What you need

Obviously, you'll need access to BitBurner. It can be found on Steam or on the internet as two seperate builds. Main (stable) or Dev
Yes, that's it!

JavaScript
Advanced
- TypeScript

JavaScript

Now, if we covered all of JavaScript then this would be a web development course, not a guide on BitBurner. As such, we'll be focusing on the basic concepts that you'll need to understand everything that you create to make a fully functional hacking script. Or at least to cover everything (Along with the downsides) that the game's given basic-hack-template script has. (Almost) All lines in JavaScript should end in a semicolon (;), The exception to this is anything with Curly braces ({ }).

Variables

In JavaScript, there's 4 major parts to every variable

Declaring
Assigning
Scope
Types

Declaring

Declaring a variable is the actual process of creating it, until a variable is declared using one of the 3 key words (const, let, var) it can't be used. When a variable is declared it is initialized (Initially created) with the value undefined (More on undefined in Types)

Const. Immutable, cannot be changed after declaration. Intended for things you know you will use throughout the code but won't ever be changed. Conforms to Block Scope.
Let. Mutable, can be changed after declaration. Intended for defaulting to one value then changing it later depending on a condition or if a variable in general needs updating. Conforms to Block Scope.
Var. Should NEVER be used unless you know exactly what you're doing and why. Many people will instantly correct your usage of var to let when you ask for help. Mutable like let is, and conforms to Function Scope. It's such bad practice to use, unless you know what you're doing, that var will not be covered for the rest of this guide. DO NOT USE!!!

const x; // This is invalid syntax, more on this in the next section.

let x;

Assigning

Assigning a variable is what actually gives/changes a variable's data. This is done by putting an equals sign (=) after the variable's name, then after the equals sign sets the value of the variable to that.

const x = "Hello World!";

Note: Although let can be split as shown below const variables MUST be in one line

let x;
x = "Hello World!";

Something almost everyone does is combine the declaration and assignment into a single line, like is done with const.

Scope

In JavaScript, as well as most languages, such a thing exists called Scope. This referrs to where things that are declared can and can't be used, and is usually defined as each set of { } being a "block." Code inside of a block can use any variables, classes, functions, and so on which are declared in a higher block or in the current block, given it has been created. However anything in lower blocks cannot be accessed from a block higher than that.

Perhaps this is slightly confusing, here's an example of scope.

export async function main() {
 const msg = "Hello World!";
 if (msg === "Hello World!") {
  let foo = 1;
  console.log(foo); // Prints 1 to the console
  console.log(msg); // Prints the string "Hello World!" to the console.
 }
 console.log(msg); // Prints the string again to the console
 foo = 2; // Throws an error saying foo is undefined, this is because foo is in a lower block scope than here and cannot be accessed from here.
 console.log(foo); // Code is never reached, but if it was run it would throw an error because of foo being undefined
}

What we first do is we define a new variable, msg, and initialize it with the value "Hello World!" This is a const variable and cannot be changed later, if we attempted to reassign a value to it (Such as msg = "I've been changed...") it would throw an error. Then we check to see if the value of msg is equal to "Hello World!", which it is. This runs the code inside of the pair of curly braces, which is a new block level. Inside of this new block level, we declare the variable foo and initialize it with a value of 1. After that we print the value of foo to the console, then print the value of msg to the console. Now we have exited the scope of the if function and the variable foo disappears. We print the value of msg to the console again, and then we try to assign a value of 2 to the variable foo. Because foo has in essence disappeared an error is thrown saying that foo is undefined, because it literally is not in the scope.

If statements

If statements are an extremely powerful, versetile, and useful tool in every programming language. They allow you to not just carry out a set of instructions, but add logic to your code.

Fireball5939/BGBBJS