# Glossary

# General

# Array

An array is an ordered collection of data (either primitive or object depending upon the language). Arrays are used to store multiple values in a single variable. This is compared to a variable that can store only one value.

Each item in an array has a number attached to it, called a numeric index, that allows you to access it. In JavaScript, arrays start at index zero and can be manipulated with various methods.

const principals = ['Jared', 'Kim', 'Mike', 'Scott', 'Tito'];

console.log(principals[0]);
// Output: 'Jared'

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# Constant

A constant is a value that the programmer cannot change, for example numbers (1, 2, 42). With variables, on the other hand, the programmer can assign a new value to a variable name already in use.

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# CSS

Cascading Style Sheets (CSS) is a stylesheet language used to describe the presentation of a document written in HTML or XML (including XML dialects such as SVG, MathML or XHTML). CSS describes how elements should be rendered on screen, on paper, in speech, or on other media.

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# end, Back

In many cases, most of the code to support a dynamic website must run on a server, and not the machine that displays the website. The server environment is oftern referred to as the "back-end", and creating this code is known as server-side or back-end development.

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# end, Front

Essentailly, the converse of back-end. The portion of a website that runs on the machine displaying it, such as the design, static content, and interactive scripting, is known as the "front-end." Creating this code is often referred to as front-end development.

# Expression

# Function

# Git

# HTML

HTML (HyperText Markup Language) is the most basic building block of the Web. It defines the meaning and structure of web content. HTML uses markup to annotate text, images, and other content for display in a Web browser. HTML markup is organized with elements. An HTML element is set off from other text in a document by tags, which consist of the element name surrounded by < and >.

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# HyperText

Links that connect web pages to one another, either within a single website or between websites.

# Index (file structure)

In the directory structure of a website or web application, a file with the name of index typically serves as the entry point for the contents of the folder it's in. Certain default behaviors are associated with files named index, depending on the file type and the runtime environment.

For example, a file named index.html will automatically be served as a website's default page at http://website.com/ by most web servers. A file named index.js typically contains a list of the modules exported by the contents of the folder it's in.

# Index (programming)

A numerical description of a value's position within a set, such as an array. Indicies are consecutive integers, increment by 1, and typically begin at 0 for the first item in the set.

# JavaScript

JavaScript (JS) is a lightweight programming language with first-class functions. While it is most well-known as the scripting language for Web pages, many non-browser environments also use it, such as Node.js, Apache CouchDB and Adobe Acrobat. JavaScript is a prototype-based, multi-paradigm, single-threaded, dynamic language, supporting object-oriented, imperative, and declarative (e.g. functional programming) styles.

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# Markup

A markup language is one that is designed for defining and presenting text. HTML (HyperText Markup Language), is an example of a markup language. Within a text file such as an HTML file, elements are marked up using tags which explain the purpose of that part of the content.

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# Method

# Object

Object refers to a data structure containing data and instructions for working with the data. JavaScript, Java, C++, Python, and Ruby are examples of object-oriented programming languages.

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# Object-oriented [programming]

Object-Oriented Programming is an approach in programming in which data is encapsulated within objects and the object itself is operated on, rather than its component parts.

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# Scope

The current context of execution. The context in which values and expressions are "visible" or can be referenced. If a variable or other expression is not "in the current scope," then it is unavailable for use. Scopes can also be layered in a hierarchy, so that child scopes have access to parent scopes, but not vice versa.

A function serves as a closure in JavaScript, and thus creates a scope, so that (for example) a variable defined exclusively within the function cannot be accessed from outside the function or within other functions.

For instance, the following is invalid:

function exampleFunction() {
    const x = "locally scoped"; // x can only be used in exampleFunction
    console.log(x); // Output: 'locally scoped'
}

console.log(x); // Output: 'undefined'

However, the following code is valid due to the variable being declared outside the function, making it global:

const x = "globally scoped"; // x can be used anywhere

function exampleFunction() {
    console.log(x); // Output: 'globally scoped'
}

console.log(x); // Output: 'globally scoped'

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# Stylesheet

# Variable

A variable is a named location for storing a value. That way an unpredictable value can be accessed through a predetermined name.

MDN Reference

# HTML

# Attribute (HTML)

# Content model

# content, Embedded

# content, Flow

# content, Heading

# content, Interactive

# content, Metadata

# content, Phrasing

# content, Sectioning

# Document

# Document body

# Document head

# Element

# id

# Namespace

# Semantic

# SVG

# Tag

# CSS

# Attribute (CSS)

# BEM

# Box model

# Cascading

# Class

# Property

# Pseudo element

# Selector

# Specificity

# JavaScript

# Block

A block statement is used to group zero or more statements. The block is delimited by a pair of curly brackets { } and may optionally be labelled, with a prefix statement such as if.

MDN Reference

# Console

# Const

const feetPerMile = 5280;

feetPerMile = 100;
// Will cause an error, like: TypeError: invalid assignment to const `feetPerMile'

console.log(feetPerMile);
// Output: 5280

Constants are block-scoped, much like variables defined using the let statement. The value of a constant can't be changed through reassignment, and it can't be redeclared.

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# Framework

# JSON

# Let

let currentTemperature = 65;
console.log(currentTemperature);
// Output: 65

currentTemperature = 61;
console.log(currentTemperature);
// Output: 61

The let statement declares a block scope local variable, optionally initializing it to a value.

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# Module

# Package

# Package manager

# Parameter

# Prop

# Property

# Request