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glossary/README.md

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+# 30-seconds-of-code JavaScript Glossary
+
+## Table of Contents
+
+* [`Array`](#array)
+* [`Boolean`](#boolean)
+* [`Callback`](#callback)
+* [`Cross-site scripting (XSS)`](#cross-site-scripting-xss)
+* [`Currying`](#currying)
+* [`DNS`](#dns)
+* [`DOM`](#dom)
+* [`Domain name`](#domain-name)
+* [`Element`](#element)
+* [`Event loop`](#event-loop)
+* [`Functional programming`](#functional-programming)
+* [`Functor`](#functor)
+* [`HTTP and HTTPS`](#http-and-https)
+* [`JSON`](#json)
+* [`Object-oriented programming`](#object-oriented-programming)
+* [`Promise`](#promise)
+* [`Recursion`](#recursion)
+* [`Regular expressions`](#regular-expressions)
+* [`Selector`](#selector)
+* [`String`](#string)
+* [`Template literals`](#template-literals)
+* [`Value vs reference`](#value-vs-reference)
+
+
+### Array
+
+Arrays are used to store multiple values in a single variable.
+Arrays are ordered and each item in an array has a numeric index associated with it.
+JavaScript arrays are zero-indexed, meaning the first element's index is 0.
+
+### Boolean
+
+Booleans are one of the primitive data types in JavaScript. 
+They represent logical data values and can only be `true` or `false`.
+
+### Callback
+
+A callback function, also known as a high-order function, is a function that is passed into another function as an argument, which is then executed inside the outer function.
+Callbacks can be synchronous or asynchronous.
+
+### Cross-site scripting (XSS)
+
+XSS refers to client-side code injection where the attacker injects malicious scripts into a legitimate website or web application. 
+This is often achieved when the application does not validate user input and freely injects dynamic HTML content.
+
+### Currying
+
+Currying is a way of constructing functions that allows partial application of a function's arguments.
+Practically, this means that a function is broken down into a series of functions, each one accepting part of the arguments.
+
+### DNS
+
+A DNS (Domain Name System) translates domain names to the IP addresses needed to find a particular computer service on a network.
+
+### DOM
+
+The DOM (Document Object Model) is a cross-platform API that treats HTML and XML documents as a tree structure consisting of nodes. 
+These nodes (such as elements and text nodes) are objects that can be programmatically manipulated and any visible changes made to them are reflected live in the document. 
+In a browser, this API is available to JavaScript where DOM nodes can be manipulated to change their styles, contents, placement in the document, or interacted with through event listeners.
+
+### Domain name
+
+A domain name is a website's address on the Internet, used primarily in URLs to identify the server for each webpage.
+A domain name consists of a hierarchical sequence of names, separated by dots and ending with an extension.
+
+### Element
+
+A JavaScript representation of a DOM element commonly returned by `document.querySelector()` and `document.createElement()`. 
+They are used when creating content with JavaScript for display in the DOM that needs to be programatically generated.
+
+### Event loop
+
+The event loop handles all asynchronous callbacks. 
+Callbacks are queued in a loop, while other code runs, and will run one by one when the response for each one has been received.
+The event loop allows JavaScript to perform non-blocking I/O operations, despite the fact that JavaScript is single-threaded.
+
+### Functional programming
+
+Functional programming is a paradigm in which programs are built in a declarative manner using pure functions that avoid shared state and mutable data. 
+Functions that always return the same value for the same input and don't produce side effects are the pillar of functional programming.
+
+### Functor
+
+A Functor is a data type common in functional programming that implements a `map` method. 
+The `map` method takes a function and applies it to the data in the Functor, returning a new instance of the Functor with the result.
+JavaScript `Array`s are an example of the Functor data type.
+
+### HTTP and HTTPS
+
+The HyperText Transfer Protocol (HTTP) is the underlying network protocol that enables transfer of hypermedia documents on the Web, usually between a client and a server.
+The HyperText Transfer Protocol Secure (HTTPS) is an encrypted version of the HTTP protocol, that uses SSL to encrypt all data transfered between a client and a server.
+
+### JSON
+
+JSON (JavaScript Object Notation) is a format for storing and exchanging data.
+It closely resembles the JavaScript object syntax, however some data types, such as dates and functions, cannot be natively represented and need to be serialized first.
+
+### Object-oriented programming
+
+Object-oriented programming (OOP) is a programming paradigm based on the concept of objects, which may contain both data and procedures which can be use to operate on them.
+JavaScript supports Object-oriented programming both via prototypes and classes.
+
+### Promise
+
+The Promise object represents the eventual completion (or failure) of an asynchronous operation, and its resulting value.
+A Promise can be in one of these states: pending(initial state, neither fulfilled nor rejected), fulfilled(operation completed successfully), rejected(operation failed).
+
+### Recursion
+
+Recursion is the repeated application of a process. 
+In JavaScript, recursion involves functions that call themselves repeatedly until they reach a base condition. 
+The base condition breaks out of the recursion loop because otherwise the function would call itself indefinitely. 
+Recursion is very useful when working with nested data, especially when the nesting depth is dynamically defined or unkown.
+
+### Regular expressions
+
+Regular expressions (known as regex or regexp) are patterns used to match character combinations in strings.
+JavaScript provides a regular expression implementation through the `RegExp` object.
+
+### Selector
+
+A CSS selector is a pattern that is used to select and/or style one or more elements in a document, based on certain rules.
+The order in which CSS selectors apply styles to elements is based on the rules of CSS specificity.
+
+### String
+
+Strings are one of the primitive data types in JavaScript.
+They are sequences of characters and are used to represent text.
+
+### Template literals
+
+Template literals are strings that allow embedded expressions.
+They support multi-line strings, expression interpolation and nesting.
+
+### Value vs reference
+
+When passing a variable by value, a copy of the variable is made, meaning that any changes made to the contents of the variable will not be reflected in the original variable.
+When passing a variable by reference, the memory address of the actual variable is passed to the function or variable, meaning that modifying the variable's contents will be reflected in the original variable.
+In JavaScript primitive data types are passed by value while objects are passed by reference.

glossary/keyword_database

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+array
+boolean
+callback
+cross-site-scripting-xss
+currying
+dns
+dom
+domain-name
+element
+event-loop
+functional-programming
+functor
+http-and-https
+json
+keyword_database
+object-oriented-programming
+promise
+readme
+recursion
+regular-expressions
+selector
+string
+template-literals
+value-vs-reference