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Introduction...................1 Parlez-Vous JavaScript? 2 Contacting Me/Getting Help...................... 2 1 Hello, World!... 5 What Is JavaScript?....... 7 Hello, World!.................. 9 Statements, Expressions, and Functions..12 I The Basic Stuff 2 Values and Variables..................... 15 Using Variables............16 More Variable Stuff......18 3 Functions....... 23 What Is a Function?.....26 A Simple Function.......26 Creating a Function That Takes Arguments...........................30 Creating a Function That Returns Data...35 4 Conditional Statements: if, else, and switch............... 39 The If/Else Statement..40 Switch Statements.......49 Deciding Which to Use..............................55 5 Looping with for, while, and do...while!...................... 57 The for Loop................59 The Starting Point........62 Some for Loop Examples..........................64 The Other Loops.........67 6 Commenting Your Code...FTW!.... 71 What Are Comments?.72 Commenting Best Practices......................76 7 Timers............ 79 Delaying with setTimeout..........................80 8 Variable Scope.............................. 85 Global Scope...............86 Local Scope..................88 Miscellaneous Scoping Shenanigans.......89 9 Closures......... 95 Functions Within Functions.......................96 When the Inner Functions Aren''t Self-Contained................100 10 Where Should Your Code Live?.. 109 Approach #1: All the Code Lives in Your HTML Document...................113 Approach #2: The Code Lives in a Separate File................114 So, Which Approach to Use?..................118 11 Console Logging Basics.............. 123 Meet the Console......124 Displaying the Console............................126 If You Want to Follow Along...................127 Console Logging
101..............................128 II It''s an Object-Oriented World 12 Of Pizza, Types, Primitives, and Objects................... 135 Let''s First Talk About Pizza.......................136 From Pizza to JavaScript!.........................139 What Are Objects?....141 The Predefined Objects Roaming Around in JavaScript....142 13 Arrays.......... 145 Creating an Array......146 Accessing Array Values............................147 Adding Items.............149 Removing Items.........151 Finding Items.............152 Merging Arrays..........152 Mapping, Filtering, and Reducing Arrays.............................153 The Old School Way.153 Modifying Each Array Item with map.....154 Getting One Value from an Array of Items...........................157 A Short Foray into Functional Programming........................160 14 Strings......... 161 The Basics...................162 String Properties and Methods...............163 15 Combining Strings and Variables 173 Our Setup...................174 16 When Primitives Behave Like Objects....................... 179 Strings Aren''t the Only Problem.............180 Let''s Pick on Strings Anyway...................180 Why This Matters.......182 17 Numbers...... 185 Using a Number........186 Operators...................187 Incrementing and Decrementing............188 Hexadecimal and Octal Values...............190 Special Values--Infinity and NaN...........190 The Math Object.......191 Random Numbers.....196 18 Getters and Setters.................... 201 A Tale of Two Properties..........................202 Meet Getters and Setters........................205 19 A Deeper Look at Objects.......... 211 Meet the Object........212 Creating Custom Objects........................222 The this Keyword.......226 20 Using Classes.............................. 231 The Class Syntax and Object Creation..232 Extending Objects.....240 21 Extending Built-in Objects.......... 247 Say Hello to prototype Again, Sort Of!..249 Using a Subclassing Approach................253 Extending Built-in Objects Is Controversial................255 22 Arrow Functions......................... 259 What Are Arrow Functions?.....................260 Putting It All Together..............................263 23 Making Sense of this and More.. 265 The this Keyword
101..............................266 24 Booleans and the Stricter === and !== Operators... 277 The Boolean Object..278 The Boolean Function..............................278 Strict Equality and Inequality Operators281 25 Null and Undefined.................... 283 Null..............................284 Undefined...................284 26 All About JSON (JavaScript Object Notation).......... 287 What Is JSON?...........288 Looking Inside a JSON Object...............292 Reading JSON Data..297 Writing JSON Data?..300 III Working with the DOM 27 JS, the Browser, and the DOM... 303 What HTML, CSS, and JavaScript Do....304 HTML Defines the Structure....................304 Prettify My World, CSS!...........................306 It''s JavaScript Time!...307 Meet the Document Object Model........309 28 Finding Elements in the DOM.... 315 Meet the querySelector Family...............316 It Really Is the CSS Selector Syntax........318 29 Modifying DOM Elements.......... 321 DOM Elements Are Objects, Sort Of!....322 Let''s Actually Modify DOM Elements.....324 30 Styling Our Content................... 337 Why Would We Set Styles Using JavaScript?..............338 A Tale of Two Styling Approaches..........338 31 Using CSS Custom Properties.... 345 What Are CSS Custom Properties/Variables?................346 Setting Complex Values Easily................348 32 Traversing the DOM................... 353 Finding Your Way Around........................354 Putting It All Together..............................358 33 Creating and Removing DOM Elements.................... 363 Creating Elements.....364 Removing Elements..372 Cloning Elements......374 34 Quickly Adding Many Elements into the DOM......... 381 General Approach.....383 Getting Started..........384 35 In-Browser Developer Tools........ 397 Meet the Developer Tools.......................398 IV Dealing with Events 36 Events.......... 417 What Are Events?......418 Events and JavaScript..............................420 A Simple Example.....423 The Event Arguments and the Event Type.............426 37 Event Bubbling and Capturing... 429 Event Goes Down, Event Goes Up........430 Meet the Phases........434 Who Cares?................437 Event, Interrupted.....438 38 Mouse Events............................. 443 Meet the Mouse Events...........................444 The MouseEvent Properties....................451 Dealing with the Mouse Wheel..............454 39 Keyboard Events........................ 457 Meet the Keyboard Events........