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Essential JavaScript

Introduction

Running Code
Learning Goals
JavaScript Intro

JavaScript Basics

The Console
Errors
Expressions
Comments
Functions
Arguments
The First Kata

Numbers

Add and Subtract
Plant Purchase Kata
Multiply and Divide
Apple Baskets Kata
Cake Slices Kata
Modulus and Remainders
Dogs and Bones Kata
Order of Operations
Flower Food Kata

Strings

Strings Intro
Concatenation
Hello Kata
Interpolation
Phrase Builder Kata
Using Quotes in a String
Escaping Characters
String Length
Name Length Kata
String Characters

Logic

Boolean Values
Comparison Operators
Strict Equality
Equal Values Kata
Conditionals (if)
You Must Be This Tall Kata
Conditionals (else)
Sorting Shoes Kata
Biggest Pumpkin Kata
Order of Operations 2
Team Scores Kata
AND Operator
In Range Kata
Leap Year Kata
OR Operator
Vegetarian Menu Kata
FizzBuzz Kata

Variables

Variables
Empty Variables
Utilizing Variables
Naming Variables
Dance Class Kata
Shorthand Math
Increment / Decrement
Blocks
Variables with Let
Variables with Const
Variables Summary

Loops

While Loop
Looping Over Numbers
Looping Over Strings
Count Letters Kata
Breaking a Loop
Button Combo Kata
Continuing a Loop
Picky Numbers Kata
Do...While Loop
For Loop
Reverse Word Kata
Nested Loops
Stretchy Word Kata

Objects

Intro to Objects
Making Objects
Objects vs Primitives
Build-a-Bot Kata
Accessing Properties
Updating Properties
Full Name Kata
Age Verification Kata
Const Objects
Nested Objects
Object Methods

Arrays

Arrays Intro
Making Arrays
Array Builder Kata
Array Elements
Human Names Kata
Array Length
Longest Array Kata
Looping Over Arrays
Highest Number Kata
Word Hunter Kata
Array Average Kata
Min-Max Kata
Adding Elements
Number Range Kata
Removing Elements
Arrays of Objects
Biggest Animal Kata
Arrays of Arrays
Taboo Words Kata

Going Further

What Next?
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Add and Subtract

We have already seen how JavaScript can do math.

We can add and subtract any number of numbers together:

1 + 2 + 17 - 9 + 5 - 4

And we get 12 as a result.

Negative Numbers

What happens when you subtract 2 from 1?

You get -1, of course. JavaScript knows this. JavaScript understands negative numbers and is happy to work with them as well.

Try running: 1 - 2

Try running: -1 + 2

Try running: -2 + -3

Try running: 1 - -2

Learning Goals

  • I can add numbers in JavaScript

  • I can subtract numbers in JavaScript

  • I can work with negative numbers in JavaScript

Code Editor

Click "Run Code" to execute your JavaScript in a secure sandbox and see the output below.

Console Output

// Console output will appear here...

0 output lines