A

Arguments The values you provide (or pass in) to a function.

Array A data structure that allows you to store and access a sequence of values.

B

Boolean A data structure that represents true or false.

C

Cascading Style Sheets (CSS) A styling language used primarily for changing how the content in your HTML page looks.

Closure An inner function that has access to an outer function’s variables (in addition to its own and any global variables).

Comments Human readable text (often separated by // or /* and */ characters) in your code that is completely ignored by JavaScript.

D

Developer Tools In the context of browsers, they are extensions that help you inspect, debug, and diagnose what is going on inside your web page.

Do...While Loop A control statement that executes some code until a condition you specify returns false. (This is great if you don’t know how many times you want to loop!)

Document Object Model (DOM) The JavaScript representation (often in a tree-like structure) of your HTML page and all the things inside it.

E

Event Bubbling The phase where an event starts at the element that initiated the event and climbs the DOM back to the root.

Event Capturing The phase where an event starts at the root and traverses down the DOM until it reaches the element that initiated the event.

Event Listener A function that listens for an event and then executes some code when that event is overheard.

Event Target The element that is responsible for having initiated (aka fired) an event.

Event A signal that travels through your DOM to indicate something has happened.

F

For Loop A control statement that executes some code a finite number of times.

Function A reusable block of code that takes arguments, groups statements together, and can be called on to execute the code contained inside it.

G

Global Scope Something declared outside of a function that is accessible to the entire app.

I

If Statement A conditional statement that executes some code if the condition is true.

If/Else Statement A conditional statement that executes different pieces of code depending on whether a condition is true or false.

IIFE (Immediately Invoked Function Expression) A way of writing JavaScript that allows you to execute some code in its own scope without leaving behind any trace of its existence.

Invoke A fancy way of saying the same thing as calling a function.

J

JavaScript A fussy and (often) inconsistent scripting language that, to everyone’s surprise over the years, has grown to be quite popular for building apps on the web and the server.

L

Local Scope Something that is accessible only to the enclosing function or block.

Loop A control statement that allows you to execute code repeatedly.

N

Node A generic name for an item in the DOM.

O

Object A very flexible and ubiquitous data structure you can use to store properties and their values and...even other objects.

Operators A built-in function such as your friendly +, -, *, /, for, while, if, do, =, etc. words.

P

Primitives A basic type that isn’t composed of other types.

R

Return A keyword that exits a function or block. In the case of functions, it is often used to return some data back to whatever called the function.

S

Scope A term indicating the visibility of something. In the real world, it is also a brand of mouthwash.

Strict Equality (===) Comparison Checks whether value and type of two things is equal.

Strict Inequality (!==) Comparison Checks whether the value and type of two things is not equal.

String A sequence of characters that make up what we think of as text. It is also the name of a formal type for dealing with text in JavaScript.

Switch Statement A conditional statement that checks a particular condition against a list of cases. If one of the cases matches the condition, the code associated with that case executes.

T

Timer Functions Functions that execute code at a periodic interval. The most common timer functions are setTimeOut, setInterval, and requestAnimationFrame.

Type A classification that helps identify your data and the values you can use.

V

Values The formal name for the various types of data you’ll encounter.

Variable Scope The term for describing the visibility of a variable in a section of code.

Variables A named bucket for storing some data.

W

Weak Equality (==) Comparison Checks only whether the value of two things is equal.

Weak Inequality (!=) Comparison Checks only whether the value of two things is unequal.

Web Browser A complex application that, at its bare minimum, helps you browse the Internet and display web pages.

While Loop A control statement that continually executes some code until a condition you specify returns false.