Eloquent JavaScript: A Modern Introduction to Programming

450 Pages·2018·16.98 MB·english

by  Marijn Haverbeke

Master the Language
of the Web
3rd Edition
E
JavaScript lies at the heart of almost every a browser game, a simple programming lan-
l
modern web application, from social apps like guage, and a paint program, you’ll learn how to:
o
Twitter to browser-based game frameworks.
 Understand the essential elements of pro-
Though simple for beginners to pick up and
gramming, including syntax, control, and data
q
play with, JavaScript is a flexible, complex
 Organize and clarify your code with object-
language that you can use to build full-scale u third Edition
oriented and functional programming
applications.
techniques
e
This third edition of Eloquent JavaScript
 Script the browser and make basic web
dives deep into the JavaScript language to show n
applications
you how to write beautiful, effective code. The
A Modern Introduction
updates include brand-new material on features  Use the DOM effectively to interact with t
like class notation, arrow functions, iterators, browsers to Programming

async functions, template strings, and block J
 Harness Node.js to build servers and utilities
scope. a
Isn’t it time you became fluent in the language
Haverbeke immerses you in code from the v Marijn Haverbeke
of the web?
start and teaches through extensive examples, a
while exercises and full-chapter projects give
About the Author
S
you hands-on experience writing your own
programs. First you’ll learn the basic structure Marijn Haverbeke is a programming language c
of the JavaScript language as well as control
enthusiast and polyglot. He’s worked on a wide
r
structures, functions, and data structures.
range of software systems, from databases to
Then you’ll learn about error handling and
compilers to editors. He runs a small business i
bug fixing, modularity, and asynchronous pro- around his open source projects. p
gramming before moving on to programming
t
web browsers. As you build projects such as All source code is available online in an interactive
sandbox, where you can edit the code, run it, and see
its output instantly.
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THE FINEST IN GEEK ENTERTAINMENT™ Price: $39.95 ($53.95 CDN)
www.nostarch.com e
Shelve In: Programming Languages/JavaScript k
e

Praise for the first and second editions of
EloquEnt JavaScript
“Provides some of the best explanations of programming concepts that I’ve
ever read.”
—Sandra Henry-Stocker, It World
“If you choose to start your JavaScript journey with this book, it can quickly
teach you a lot of technical information and also programming wisdom.”
—MIcHael J. roSS, Web developer and SlaSHdot contrIbutor
“I became a better architect, author, mentor and developer because of this
book. It deserves to share shelf space with Flannagan and Crockford.”
—anguS croll, tWItter developer
“The best introduction into any programming language and programming
overall. Period.”
—Jan leHnardt, co-creator of HoodIe and organIzer of JSconf eu
“This is the book I give out when people ask me how to learn proper
JavaScript.”
—cHrIS WIllIaMS, organIzer of JSconf uS
“One of the best JavaScript books I’ve read.”
—rey bango, JQuery teaM MeMber and clIent-Web coMMunIty prograM
Manager at MIcroSoft
“A really good guide to JavaScript; but even more than that, this book is a
great guide to programming.”
—ben nadel, cHIef SoftWare engIneer at epIcenter conSultIng
“A good book, suitable for those without experience in JavaScript and even
those without programming experience.”
—nIcHolaS zakaS, autHor of HigH Performance JavaScriPt and
tHe PrinciPleS of obJect-oriented JavaScriPt
“If you’re new to JavaScript, the first thing I’d recommend you do is visit
Eloquent JavaScript and check out Marijn Haverbeke’s introduction to the
language.”
—cnet uk

E l o q u E n t
J a v a S c r i p t
a Modern introduction
to programming
by Marijn haverbeke
San Francisco
EloquEnt JavaScript, 3rd Edition. Copyright © 2019 by Marijn Haverbeke.
All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means,
electronic or mechanical, including photocopying, recording, or by any information storage or retrieval
system, without the prior written permission of the copyright owner and the publisher.
ISBN-10: 1-59327-950-7
ISBN-13: 978-1-59327-950-9
Publisher: William Pollock
Production Editor: Riley Hoffman
Cover Illustration: Madalina Tantareanu
Interior Design: Octopod Studios
Developmental Editor: Corbin Collins
Technical Reviewer: Angus Croll
Copyeditor: Kim Wimpsett
Compositor: Riley Hoffman
Proofreader: James M. Fraleigh
Chapter illustrations by Madalina Tantareanu. Pixel art in Chapters 7 and 16 by Antonio Perdomo
Pastor. Regular expression diagrams in Chapter 9 generated with Regexper by Jeff Avallone (http://
regexper.com/). Village photograph in Chapter 11 by Fabrice Creuzot. Game concept for Chapter 15 by
Thomas Palef (http://lessmilk.com/).
For information on distribution, translations, or bulk sales, please contact No Starch Press, Inc. directly:
No Starch Press, Inc.
245 8th Street, San Francisco, CA 94103
phone: [phone]; [email protected]
www.nostarch.com
The Library of Congress has catalogued the first edition as follows:
Haverbeke, Marijn.
Eloquent JavaScript: a modern introduction to programming / by Marijn Haverbeke.
p. cm.
Includes index.
ISBN-13: 978-1-59327-282-1
ISBN-10: 1-59327-282-0
1. JavaScript (Computer program language) I. Title.
QA76.73.J39H38 2009
005.13'3--dc22
2010032246
No Starch Press and the No Starch Press logo are registered trademarks of No Starch Press, Inc. Other
product and company names mentioned herein may be the trademarks of their respective owners. Rather
than use a trademark symbol with every occurrence of a trademarked name, we are using the names only
in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the
trademark.
The information in this book is distributed on an “As Is” basis, without warranty. While every precaution
has been taken in the preparation of this work, neither the author nor No Starch Press, Inc. shall have any
liability to any person or entity with respect to any loss or damage caused or alleged to be caused directly or
indirectly by the information contained in it.
BRIEF CONTENTS
Introduction......................................................................... 1
PARTI:LANGUAGE
Chapter1:Values,Types,andOperators.............................................. 11
Chapter2:ProgramStructure......................................................... 23
Chapter3:Functions................................................................. 41
Chapter4:DataStructures: ObjectsandArrays........................................ 59
Chapter5:Higher-OrderFunctions.................................................... 83
Chapter6:TheSecretLifeofObjects.................................................. 97
Chapter7:Project: ARobot.......................................................... 117
Chapter8:BugsandErrors .......................................................... 129
Chapter9:RegularExpressions....................................................... 145
Chapter10:Modules................................................................ 167
Chapter11:AsynchronousProgramming .............................................. 181
Chapter12:Project: AProgrammingLanguage ........................................ 203
PARTII:BROWSER
Chapter13:JavaScriptandtheBrowser............................................... 219
Chapter14:TheDocumentObjectModel ............................................. 227
Chapter15:HandlingEvents......................................................... 247
Chapter16:Project: APlatformGame ................................................ 265
Chapter17:DrawingonCanvas ..................................................... 287
Chapter18:HTTPandForms......................................................... 311
Chapter19:Project: APixelArtEditor ................................................ 333
PARTIII:NODE
Chapter20:Node.js ................................................................ 353
Chapter21:Project: Skill-SharingWebsite............................................. 371
Chapter22:JavaScriptandPerformance .............................................. 391
ExerciseHints....................................................................... 407
Index............................................................................... 429
vi BriefContents
CONTENTS IN DETAIL
INTRODUCTION 1
OnProgramming................................................................. 2
WhyLanguageMatters ........................................................... 3
WhatIsJavaScript? .............................................................. 5
Code,andWhattoDowithIt ..................................................... 6
OverviewofThisBook............................................................ 7
TypographicConventions ......................................................... 8
PART I: LANGUAGE
1
VALUES, TYPES, AND OPERATORS 11
Values .......................................................................... 12
Numbers ........................................................................ 12
Arithmetic............................................................... 13
SpecialNumbers ........................................................ 14
Strings .......................................................................... 14
UnaryOperators ................................................................. 16
BooleanValues .................................................................. 16
Comparison............................................................. 16
LogicalOperators........................................................ 17
EmptyValues .................................................................... 18
AutomaticTypeConversion ....................................................... 18
Short-CircuitingofLogicalOperators....................................... 19
Summary ........................................................................ 20
2
PROGRAM STRUCTURE 23
ExpressionsandStatements ....................................................... 23
Bindings......................................................................... 24
BindingNames .................................................................. 26
TheEnvironment.................................................................. 26
Functions ........................................................................ 26
Theconsole.logFunction.......................................................... 27
ReturnValues .................................................................... 27
ControlFlow..................................................................... 28
ConditionalExecution............................................................. 28
whileanddoLoops............................................................... 30
IndentingCode .................................................................. 32
forLoops ........................................................................ 32
BreakingOutofaLoop ........................................................... 33
UpdatingBindingsSuccinctly...................................................... 34
DispatchingonaValuewithswitch ................................................ 34
Capitalization.................................................................... 35
Comments....................................................................... 35
Summary ........................................................................ 36
Exercises ........................................................................ 37
LoopingaTriangle....................................................... 37
FizzBuzz................................................................ 37
Chessboard ............................................................. 38
3
FUNCTIONS 41
DefiningaFunction............................................................... 41
BindingsandScopes ............................................................. 43
NestedScope ........................................................... 44
FunctionsasValues............................................................... 44
DeclarationNotation ............................................................. 45
ArrowFunctions.................................................................. 45
TheCallStack ................................................................... 46
OptionalArguments .............................................................. 47
Closure.......................................................................... 48
Recursion........................................................................ 50
GrowingFunctions ............................................................... 52
FunctionsandSideEffects......................................................... 54
Summary ........................................................................ 55
Exercises ........................................................................ 56
Minimum................................................................ 56
Recursion ............................................................... 56
BeanCounting .......................................................... 56
4
DATA STRUCTURES: OBJECTS AND ARRAYS 59
TheWeresquirrel................................................................. 60
DataSets........................................................................ 60
Properties........................................................................ 61
Methods......................................................................... 62
Objects ......................................................................... 62
Mutability ....................................................................... 65
TheLycanthrope’sLog ............................................................ 66
ComputingCorrelation............................................................ 67
ArrayLoops ..................................................................... 69
viii ContentsinDetail