Glossary: Useful Definitions of Web-related Terms

This Glossary alphabetically lists the definition of important web technological terms like Git, GitHub, HTML, CSS, JavaScript, Recursion, and Data. Click any of the letters below to jump straight to the terms that begin with that letter.

A – BCDEFGHIJ – K – LMNOP – Q – RSTUVW – X – Y – Z

A

Absolute length units

Absolute length units are fixed standards of measurement. In other words, the size of things expressed in any of the absolute length units will never change — regardless of the medium used to display them.

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AND operator (JS)

The AND operator (&&) checks if all of its operands are true.

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apply()

apply() is one of JavaScript’s built-in methods that you can use to reassign a specific method from one object to a different one.

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Argument (JS)

An argument is an optional value you may pass to a function’s parameter through an invocator.

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arguments object (JS)

An arguments object is an array-like object built-in to every non–arrow function.

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Arithmetic expression (JS)

Arithmetic expressions are those that express a numeric value.

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Array-like object (JS)

An array-like object is an object that has only a few — not all — of the features of a regular JavaScript array.

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Assignment expression (JS)

Assignment expressions are those that assign their evaluated value to a variable (or property).

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ASYNC

ASYNC (asynchronous) means “not synchronous”.

Events are asynchronous if they do not need to wait for each other to complete their processing before another event’s execution begins.

In other words, when two events happen asynchronously, event B does not need to wait for event A to complete its processing before starting its own execution.

ASYNC (JS)

In JavaScript, ASYNC (asynchronous) programming refers to functions that run in their own timing — without waiting for each other to finish its execution first.

An example is the setTimeout() method that invokes its callback argument in a given time — irrespective of the ongoing execution of other functions.

Audio data

Audio data are the sound-recorded contents of a page, such as WAV, MP3, and AAC.

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B

Base case

A base case is a code written to discontinue the re-invocation of a recursive function.

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bind()

bind() is one of JavaScript’s built-in methods that you can use to reassign a specific method from one object to a different one.

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Build step

A build step is a process through which a bundler builds a new browser compatible JavaScript file.

C

call()

call() is one of JavaScript’s built-in methods that you can use to reassign a specific method from one object to a different one.

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Chunk

A chunk refers to the modified section of a file.

A chunk consists of the modified line and its context, where context means some unaltered lines before and after the modified line.

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Class component

A class component is a plain JavaScript Class that extends a user-defined class to the built-in React.Component class located inside the React library.

Code

code is any language that computers can understand and process.

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Create React App

Create React App (CRA) is an official React package used to set up React projects easily without going through the troubles of configuring build tools like Webpack or Babel.

CSS

CSS (Cascading Style Sheets) is a styling language that styles elements of an HTML document.

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CSS unit

A CSS Unit is the standard of measurement used in CSS to express the size of a specific element’s property.

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D

Data

Data is the content of a document. In order words, the text and graphics on a page are the document’s data.

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Deep copy (JS)

You do deep copy when you clone objects without creating references.

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Deep object (JS)

A deep object is one that contains a non-primitive item.

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Destructuring array (JS)

The destructuring array assignment is a unique technique you can use to copy an array’s value into new variables neatly.

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Destructuring assignment (JS)

The destructuring assignment is a unique technique you can use to copy the values of an object or array into new variables.

Destructuring object (JS)

The destructuring object assignment is a unique technique you can use to copy an object’s values into new variables neatly.

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Distribution code

A distribution code is the minified and optimized version of the source code. It is the distribution code (the build step’s output) that gets loaded to the browser.

Document

A document is a page used to contain text, or graphics, or both.

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E

Entry point

An entry point is the most critical file of a build step that links (directly or indirectly) to every other module in the project.

Equality operator (JS)

The equality operator (==) checks if its two operands are of equal value.

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Error handling phase (ReactJS)

A component’s error handling phase is the period when an error occurs in any of the following cases:

  • During the component instance’s rendering
  • In a lifecycle method of the component
  • In any child component’s constructor

Execution time

Execution time (also called runtime) is the time during which a program is running.

In other words, it is the execution period (or lifecycle phase) of a program — which begins from the time the program is invoked and ends when the program’s invocation is closed.

Expression (JS)

A JavaScript expression is any piece of code that expresses a value.

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F

Framework

A framework is a codebase written to serve as the primary structure for your application.

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Function component

A function component is a regular JavaScript function that can accept a single properties object (props) as its parameter and emits a React element as its return value.

G

Git

Git is a Distributed Version Control System (DVCS) used to save different versions of a file (or set of files) — wherein any version is retrievable at will.

Git makes it easy to record and compare different file versions. Consequently, details about what changed, who changed what, or who initiated an issue are reviewable anytime.

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GitHub

GitHub is a web-based platform for hosting (or sharing) Git repositories. It helps you facilitate easy sharing and collaboration on projects with anyone at any time.

GitHub also encourages broader participation in open-source projects by providing a secure way to edit files in another user’s repository.

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Git cloning

Git Cloning is mainly about getting (downloading) a copy of a .git repository.

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Git commit

Whenever you commit your files to Git, it means you have stored the staged version of your working directory’s file(s) into the .git repository.

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Git directory

Git directory is a folder Git creates in the working directory you instructed it to monitor.

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Git initialization

Initialization is to make Git ready to start monitoring files in a specified directory.

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Git staging

Staging implies that you have added details about your staged file(s) into a file called “index” — located in the Git directory.

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Git staging area

The staging area is a file Git uses to store details about files it is about to commit into the .git directory.

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Graphical data

Graphical data are the visual contents of a page, such as diagrams, charts, videos, and images.

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Greater than operator (JS)

The greater than operator (>) checks if its left operand is greater than its right-hand one. If so, the Boolean value true gets returned. Otherwise, the computer will return false.

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Greater than or equal to operator (JS)

The greater than or equal to operator (>=) checks if its left operand is greater than or equal to its right-hand operand. If so, the Boolean value true gets returned. Otherwise, the computer will return false.

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H

HTML

HTML (HyperText Markup Language) is an extension of plain texts. It is a note to browsers about a document’s data, thereby helping browsers present webpages accurately.

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Hyper

Hyper means Extensive (that is, an extension of another thing).

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HyperLink means ExtensiveLink (that is, a link that acts as an extension of another link).

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HyperSpace

HyperSpace means ExtensiveSpace (that is, a space that acts as an extension of another space).

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HyperText

HyperText means ExtensiveText (that is, a text that acts as an extension of another text).

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I

Impure function

An impure function is a function that contains one or more side effects.

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Iterable

An iterable is an object that has a property with a @@iterator key.

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J

JavaScript

JavaScript is a commanding language that commands the items of an HTML document.

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JSX

JSX (JavaScript and XML) is a syntax extension to JavaScript that allows you to build React elements with HTML-like syntax right inside your JavaScript code.

L

Left-hand-side expression (JS)

Left-hand-side expressions are those on the left-hand side of an assignment operator and serve as the destination of the value expressed by the right-hand expression.

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Less than operator (JS)

The less than operator (<) checks if its left operand is less than its right-hand one. If so, the Boolean value true gets returned. Otherwise, the computer will return false.

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Less than or equal to operator (JS)

The less than or equal to operator (<=) checks if its left operand is less than or equal to the one on the right-hand. If so, the Boolean value true gets returned. Otherwise, the computer will return false.

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Lexical

Lexical refers to the definition of things.

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Lexical scope

Lexical scope is the definition area of an expression.

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Lexicon

A lexicon is a dictionary where words are listed and defined.

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Library

A library is a codebase written to act as an add-on feature to your application.

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Lifecycle (ReactJS)

The lifecycle of a React component refers to the series of stages a component instance goes through from its creation to its total removal from the DOM.

Lifecycle methods (ReactJS)

Lifecycle methods are the inbuilt React methods you can use to operate on your components during their lifecycle in the DOM.

Logic (JS)

Logic is the analytical action performed by a computer, which often requires the computer to decide if a specific condition is true or false.

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Logical expression (JS)

Logical expressions are those that express the Boolean values, true or false.

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M

map() in JavaScript

map() creates a new array that contains the result of invoking map()‘s function argument on each item of the calling array.

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Markup

Markup means Annotate (that is, a note added to a piece of writing). They are the part of an HTML text that tells browsers how they should display the text.

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Method

A method is a function encased in a properties object as one of the object’s property’s values.

Minimax algorithm

A minimax algorithm is a recursive program written to find the best gameplay that minimizes any tendency to lose a game while maximizing any opportunity to win the game.

In other words, minimax is a recursive function created to help a player (the maximizer) decide on the gameplay that minimizes the maximum possibility to lose a game.

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Mounting phase (ReactJS)

A component’s mounting phase is when the component instance is being created and rendered into the DOM.

N

Non-assignment expression (JS)

Non-assignment expressions are those that do not assign their evaluated value to any variable (or property).

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Non-primitive data (JS)

Non-primitive data is any JavaScript value that can contain multiple other JavaScript values.

An object is the only non-primitive value in JavaScript. However, JavaScript objects are of four types: properties objects, array objects, function objects, and regular expression objects.

NOT equal to operator (JS)

The NOT equal to operator (!=) checks if its two operands are not of equal value. If so, the Boolean value true gets returned. Otherwise, the computer will return false.

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NOT operator (JS)

The NOT operator (!) is used to negate the Boolean value of an expression. In other words, it converts true to NOT true and false to NOT false.

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NOT strictly equal to operator (JS)

The Not strictly equal to operator (!==) checks if its two operands are strictly not of equal type and equal value. If so, the Boolean value true gets returned. Otherwise, the computer will return false.

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NPM

NPM (Node Package Manager) is a package manager (an alternative to Yarn) that automatically helps find and execute a specified package.

NPX

NPX is node’s package runner tool. It helps to automatically find and execute a specified package.

Nullish coalescing operator (JS)

The nullish coalescing operator (??) checks if its left-hand side operand is undefined or null. If so, it returns its right-hand side operand. Otherwise, it produces its left-hand side operand.

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O

OR operator (JS)

The OR operator (||) checks and returns true if one (or both) of its operands is true. Otherwise, it returns false if both of its operands are false.

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Output file

An output file is the compiled version of an entry file.

P

Primary expression (JS)

Primary expressions are those that serve as the basis of all other expressions.

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Primitive data (JS)

Primitive data is any plain JavaScript value that you can use to program a webpage and its content.

A Primitive value is neither a property nor a method. Instead, it is a plain value that you can use in a property, method, variable, or function.

JavaScript has seven Primitive values: Number, String, Boolean, undefined, Null, Symbol, and BigInt.

Pure function

A pure function is a function without any side effects.

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R

ReactJS

React is a component-based JavaScript library used to build user interfaces (UI) efficiently.

React component

A component is a JavaScript function (or class) that can accept arbitrary inputs (called “props”) and returns an element (UI).

React element

React element is the specific user interface (UI) you want to see displayed on-screen.

React props

React props are parameters used to pass arguments to components.

React setState()

setState() is the method used to update a class component’s state.

React state

React state is a built-in object used to store a component’s values that are likely to change over time.

Recursion

Recursion is a method by which a problem gets solved through iteration.

In other words, a recursive function is a function that repetitively invokes itself infinitely (or until something stops it).

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Relative length units

Relative length units are dynamic units. In other words, the sizes of things expressed in any of the relative length units will always be dependent on another length.

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Rest operator (JS)

The rest operator is used to put the rest of some specific user-supplied values into a JavaScript array.

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Rest parameter (JS)

A JavaScript rest parameter consists of the rest operator and a regular parameter.

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Rest variable (JS)

A JavaScript rest variable consists of the rest operator and a regular variable.

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Root directory

Root directory refers to the folder containing all other files and sub-folders of a specific project.

In other words, a root repository is a working directory that houses everything concerning a particular project.

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Runtime

Runtime (also called execution time) is the time during which a program is running.

In other words, it is the execution period (or lifecycle phase) of a program — which begins from the time the program is invoked and ends when the program’s invocation is closed.

S

Scope

Scope refers to the area where an item (such as a function or variable) is visible and accessible to other code.

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Scope chain

A scope chain refers to the unique spaces that exist from the scope where a variable got called to the global scope.

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Shallow copy (JS)

You do shallow copy when you create references while cloning one object into another.

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Shallow object (JS)

A shallow object is one that contains only primitive items.

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Side effect

Side effect occurs in a program whenever you use an external code in your function — which, as a result, impacts the function’s ability to perform its task.

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Source code

A source code is a code you write and edit.

Spread operator

The spread operator (...) helps you expand iterables into individual elements.

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State

State is the specific data managed by a stateful program.

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Stateful program

A stateful program is a program whose output depends on external states (events).

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Stateless program

A stateless program is one whose output does not depend on any external event.

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Strict equality operator (JS)

The strict equality operator (===) checks if its two operands are strictly of equal type and value.

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Strict mode (JS)

JavaScript’s strict mode is a way of ensuring the code in a script (or function) are strictly JavaScript code — not generic code nor mistyped JavaScript code.

You can invoke the strict mode by including the literal string "use strict"; as the first statement of your script file (or function statement).

See this article on w3schools for a good overview of how the “use strict”; code works.

String expression (JS)

String expressions are those that express a string value.

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T

Text Markup

Text Markup means Text Note (that is, the note added to a text to help typesetters (or computers) better understand how to present the marked-up text).

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Textual data

Textual data are the written contents of a page, such as letters (e.g., A, B, C), numbers (e.g., 1, 2, 3), symbols (e.g., $, #, +), and code (e.g., <input>, body { background: #A18A77; }, if (condition) { //execute code }).

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this (JS)

JavaScript’s this keyword refers to the owner object of the keyword’s method or the “this” value of an arrow function’s lexical context.

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U

Unit

A unit is anything accepted as a gauge for expressing the quantity or size of another thing.

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Unmounting phase (ReactJS)

A component’s unmounting phase is when the component’s instance is being removed from the DOM.

Updating phase (ReactJS)

A component’s updating phase is the period when the component instance is being updated.

V

Version Control System

A Version Control System (VCS) refers to the specific method employed to save a file’s versions for future references.

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W

Working directory

A working directory is a local folder you create to store all your project’s files.

As such, any folder you create anywhere on a system is a working directory.

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Y

Yarn

Yarn is a package manager (an alternative to NPM) that automatically helps find and execute a specified package.

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