How JavaScript Works: Master the Basics of JavaScript and Modern Web App Development

Table of Contents....4

About the Author....12

About the Technical Reviewer....13

Introduction....14

Chapter 1: Introduction to JavaScript....15

JavaScript Fundamentals....16

JavaScript’s Type Classification....17

What Is JavaScript Used For?....18

Writing JavaScript....19

Setting Up a Code Editor....21

Starting Up Our Code....22

How to Get Started with Writing Back-End JavaScript....23

Creating Node.js JavaScript Projects....25

JavaScript Support....26

Summary....28

Chapter 2: Code Structure and Logical Statements....29

Getting Started....29

Common Code Conventions....31

Semicolons....31

Spacing....32

Variable and Function Naming....33

JavaScript Variables....33

Setting Variables with let....34

Block Scoping with Variables....35

Setting Variables with var....36

Setting Variables with const....37

Mutation of const Variables....38

Defining Variables Without Values....39

Assignment Operators....40

Variable Concatenation....41

Template Literals....42

JavaScript Comments....43

Logical Statements....44

If…else Statements....44

Switch Statements....47

Defaulting to a Clause with Switch Statements....49

Equality with Switch Statements....49

Block Scoping with Logical Statements....50

Conditional Operator in Variables....52

Logical Statement Comparison Operators....52

Logical Statement Logical Operators....55

Summary....56

Chapter 3: Introduction to Objects, Arrays....57

Arrays....57

Getting the Length of an Array....58

Getting the Last Element of an Array....59

Array Manipulation Methods....60

Push and Unshift....61

Pop and Shift....61

Splice....62

Objects....63

Accessing Object Data....65

The Dot Notation vs. Square Brackets with Objects....66

Destructuring Objects....67

Object Mutability....69

Non-mutable objects....70

Spread Syntax or the “Three Dots”....72

Prototype-Based Programming....73

Prototypical Inheritance....75

[[Prototype]] vs. prototype (and __proto__)....77

Object Shallow and Deep Copies....79

Summary....82

Chapter 4: Loops and Iterables....83

Loops....83

Break and Continue in Loops....87

Loop Labels....87

Iteration....89

Iterables and For Loops....90

Array forEach methods....92

String Iteration....92

Iteration Protocol....93

Objects Are Not Iterable by Default....96

Summary....99

Chapter 5: References, Values, and Memory Management....100

Introduction....100

Stacks....101

The Event Loop....103

The Heap....106

Object and Reference Equality....107

Comparing Object Equality....109

Summary....110

Chapter 6: Functions and Classes....111

Introduction to Functions....111

Running Arguments with the “Three Dots”....114

Alternative Ways to Call Functions....114

Unnamed Function Expressions....115

Anonymous Functions....115

Functions with Arrow Notation....116

Functions and the “this” Keyword....116

Sloppy Mode....117

Arrow Notation Functionality with this....118

Calling Functions with Context....119

Constructor Functions in JavaScript....122

Additional Function Methods....125

Getters and Setters....126

Generator Functions....127

Classes....129

Classes and Constructor Functions....129

Class Methods....130

Class Method Types....133

Static Method Fields....134

Private Method Fields....136

Class Inheritance via Extends....136

Class Inheritance Super Keyword....139

Summary....141

Chapter 7: Types....142

Primitive Types....142

Primitive Wrappers....144

Using Wrappers to Create Types....147

The Number Type and NaN....148

Number Type Mathematics....150

Mathematical Methods....152

The Date Type....154

The Symbol Type....158

Truthy and Falsy Types....160

Truthy and Falsy Operators....161

Logical AND Operator....161

Logical OR Operator....162

Nullish Coalescing....163

Optionality....164

Summary....168

Chapter 8: Manipulating and Interacting with HTML....170

Window and Document Objects....170

The Window Object....171

The Document Object Model....173

Selecting HTML Elements....174

The Order of HTML....176

NodeLists and HTMLCollections....178

Manipulating HTML After Selection....181

Adding Events to HTML Elements....184

Creating a Modal Window....184

Creating a Counter....187

Event Types....188

Pointers, Touch, and Mouse....190

Event Capturing, Targeting, and Bubbling....191

Capturing Phase....194

Other Event Options....196

Live Data Using Events....198

Drag and Drop....201

The e variable....205

Creating New Elements with JavaScript....206

Manipulating CSS with JavaScript....210

HTMLElements and Changing Styles in JavaScript....210

Adding New Style Sheets to HTML Pages....211

Setting CSS Variables....211

Getting CSS Properties and HTML Dimensions....212

Summary....214

Chapter 9: Maps and Sets....216

Sets....216

Modifying Sets....218

Checking Set Membership....219

Checking Set Size....219

Merging Sets....219

Set Iteration and Values....220

Set Keys and Values....222

Maps....223

Retrieving Map Properties....226

Checking for Key Existence on a Map....228

Telling How Big a Javascript Map Is....228

Iterating, Merging, and Accessing Maps....229

Keys and Values in Maps....230

Serialization of Maps in JavaScript....232

Summary....233

Chapter 10: Fetching Data, APIs, and Promises....234

What Are APIs?....235

Understanding HTTP....237

RESTful Design....239

Understanding APIs Through a Node.JS Web Server....241

Testing Endpoints with Postman....247

The Benefits of APIs....247

Sending Data to APIs with JSON....249

The fetch Function....251

A Deep Dive into Fetch Options....254

body....255

mode....255

method....255

cache....256

credentials....256

headers....256

redirect....257

referrer....257

referrerPolicy....257

integrity....258

keepalive....258

Asynchronicity and Promises....259

Promise Methods: then, finally, and catch....261

catch and finally....262

The await Keyword....263

Useful Promise Methods....264

Promise.allSettled....265

Promise.all....266

Promise.race....267

Promise.any....268

Summary....269

Chapter 11: Introduction to Web APIs....270

Web APIs....270

Frequently Used Web APIs....272

URL API....273

Web Storage API....273

Web Notifications API....276

History API....277

Summary....278

Chapter 12: Errors and the Console....280

The Console Object....280

Console Errors, Debugs, Warnings, and Info....281

Console Tracing....281

Console Assertion....282

Console Timing....282

Console Counting....284

Other Useful Console Methods....285

Console Grouping....285

Console Tables....286

Errors and Exceptions....288

try…catch....289

finally....290

Generating Errors....292

Handling Specific Errors....293

Summary....294

Chapter 13: The Canvas....295

Introduction....296

Drawing and Images....298

Drawing Rectangles....298

Drawing Circles....301

Drawing Triangles....303

Drawing Images....305

Drawing Text....307

Interactivity and Creating a Drawing Application....309

Animations....313

Summary....315

Chapter 14: Web Workers and Multithreading....316

Introduction....316

Using Web Workers....318

Sending Messages to and from Web Workers....318

Restrictions on Web Workers....320

Conclusion....322

Index....323

JavaScript is a complicated language with a lot of misinformation surrounding how it works. This book provides a comprehensive introduction to JavaScript, from how it works at a technical level to how it is used to create websites and applications. Everything you need to know to start a career in JavaScript development is covered here.

How JavaScript Works begins with a practical introduction of the basics before moving into the technical underpinnings of JavaScript, detailing everything you need to know, including variables, memory storage, functions, classes, types, maps, sets and APIs. Once you’ve fully absorbed these key topics. author Jonathan Simpson will show you how to put them into practice, demonstrating how they are employed for modern web development. You’ll learn how to use JavaScript with HTML and CSS to construct web pages and applications, how to change CSS with JavaScript, and how to utilize Fetch and asynchronous operations.

Uponcompleting this book, you will have the foundational knowledge necessary to continue your journey to becoming a professional JavaScript developer.

What You Will Learn:

• Gain insight into the technical essentials of JavaScript and how it works
• Learn advanced concepts and such as memory storage and how classes, functions and objects actually work
• Explore the basic mathematical underpinnings of JavaScript
• Understand how JavaScript is used to manipulate HTML and CSS
• Obtain the tools and knowledge needed to start your career in web development

Who This Book Is For:

Anyone interested in a web development career, as well as those who may have already embarked on their careers, but who want to deepen their technical understanding of JavaScript and how it works.