JavaScript pocket reference

280 Pages·5.469 MB·English

by  Flanagan, David

THIRD EDITION
JavaScript
Pocket Reference
David Flanagan
Beijing • Cambridge • Farnham • Köln • Sebastopol • Tokyo
JavaScript Pocket Reference, Third Edition
by David Flanagan
Copyright © 2012 David Flanagan. All rights reserved.
Printed in the United States of America.
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Editor: Simon St. Laurent
Production Editor: Teresa Elsey
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Indexer: Jay Marchand
Cover Designer: Karen Montgomery
Interior Designer: David Futato
Illustrator: Robert Romano
October 1998: First Edition.
November 2002: Second Edition.
April 2012: Third Edition.
Revision History for the Third Edition:
2012-04-06 First release
See http://oreilly.com/catalog/errata.csp?isbn=9781449316853 for release de-
tails.
Nutshell Handbook, the Nutshell Handbook logo, and the O’Reilly logo are
registered trademarks of O’Reilly Media, Inc. JavaScript Pocket Reference,
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While every precaution has been taken in the preparation of this book, the
publisher and authors assume no responsibility for errors or omissions, or
for damages resulting from the use of the information contained herein.
ISBN: 978-1-449-31685-3
[M]
1333663134
Contents
Preface vii
Chapter 1: Lexical Structure 1
Comments 1
Identifiers and Reserved Words 2
Optional Semicolons 3
Chapter 2: Types, Values, and Variables 5
Numbers 6
Text 9
Boolean Values 12
null and undefined 13
The Global Object 14
Type Conversions 15
Variable Declaration 19
Chapter 3: Expressions and Operators 23
Expressions 24
Operators 28
Arithmetic Operators 32
Relational Operators 36
Logical Expressions 39
iii
Assignment Expressions 42
Evaluation Expressions 43
Miscellaneous Operators 44
Chapter 4: Statements 49
Expression Statements 51
Compound and Empty Statements 52
Declaration Statements 53
Conditionals 55
Loops 59
Jumps 64
Miscellaneous Statements 70
Chapter 5: Objects 75
Creating Objects 76
Properties 79
Object Attributes 90
Chapter 6: Arrays 93
Creating Arrays 94
Array Elements and Length 95
Iterating Arrays 96
Multidimensional Arrays 97
Array Methods 98
ECMAScript 5 Array Methods 103
Array Type 107
Array-Like Objects 107
Strings as Arrays 108
Chapter 7: Functions 111
Defining Functions 112
Invoking Functions 115
iv | Table of Contents
Function Arguments and Parameters 121
Functions as Namespaces 124
Closures 125
Function Properties, Methods, and Constructor 129
Chapter 8: Classes 133
Classes and Prototypes 134
Classes and Constructors 136
Java-Style Classes in JavaScript 141
Immutable Classes 143
Subclasses 144
Augmenting Classes 146
Chapter 9: Regular Expressions 149
Describing Patterns with Regular Expressions 149
Matching Patterns with Regular Expressions 158
Chapter 10: Client-Side JavaScript 163
Embedding JavaScript in HTML 163
Event-Driven Programming 165
The Window Object 165
Chapter 11: Scripting Documents 179
Overview of the DOM 179
Selecting Document Elements 182
Document Structure and Traversal 188
Attributes 190
Element Content 192
Creating, Inserting, and Deleting Nodes 195
Element Style 197
Geometry and Scrolling 201
Table of Contents | v
Chapter 12: Handling Events 205
Types of Events 207
Registering Event Handlers 215
Event Handler Invocation 218
Chapter 13: Networking 225
Using XMLHttpRequest 225
HTTP by <script>: JSONP 233
Server-Sent Events 236
WebSockets 237
Chapter 14: Client-Side Storage 239
localStorage and sessionStorage 240
Cookies 245
Index 251
vi | Table of Contents
Preface
JavaScript is the programming language of the Web. The over-
whelming majority of modern websites use JavaScript, and all
modern web browsers—on desktops, game consoles, tablets,
and smartphones—include JavaScript interpreters, making
JavaScript the most ubiquitous programming language in his-
tory. JavaScript is part of the triad of technologies that all Web
developers must learn: HTML to specify the content of web
pages, CSS to specify the presentation of those pages, and
JavaScript to specify their behavior. Recently, with the advent
of Node (http://nodejs.org), JavaScript has also become an im-
portant programming language for web servers.
This book is an excerpt from the more comprehensive Java-
Script: The Definitive Guide. No material from the out-of-date
second edition remains. I’m hopeful that some readers will find
this shorter and denser book more useful than the larger and
more intimidating volume from which it came. This pocket
reference follows the same basic outline as the larger book:
Chapters 1 through 9 cover the core JavaScript language, start-
ing with fundamental matters of language syntax—types, val-
ues, variables, operators, statements—and moving on to cov-
erage of JavaScript objects, arrays, functions and classes. These
chapters cover the language itself, and are equally relevant to
programmers who will use JavaScript in web browsers and
programmers who will be using Node on the server-side.
vii
To be useful, every language must have a platform or standard
library of functions for performing things like basic input and
output. The core JavaScript language defines a minimal API for
working with text, arrays, dates, and regular expressions but
does not include any input or output functionality. Input and
output (as well as more sophisticated features, such as net-
working, storage, and graphics) are the responsibility of the
“host environment” within which JavaScript is embedded. The
most common host environment is a web browser. Chapters
1 through 9 cover the language’s minimal built-in API. Chap-
ters 10 through 14 cover the web browser host environment
and explain how to use “client-side JavaScript” to create dy-
namic web pages and web applications.
The number of JavaScript APIs implemented by web browsers
has grown explosively in recent years, and it is not possible to
cover them all in a book of this size. Chapters 10 through 14
cover the most important and fundamental parts of client-side
JavaScript: windows, documents, elements, styles, events, net-
working and storage. Once you master these, it is easy to pick
up additional client-side APIs, which you can read about in
JavaScript: The Definitive Guide. (Or in Canvas Pocket Refer-
ence and jQuery Pocket Reference, which are also excerpts from
The Definitive Guide.)
Although the Node programming environment is becoming
more and more important, there is simply not room in this
pocket reference to include any information about server-side
JavaScript. You can learn more at http://nodejs.org. Similarly,
there is no room in the book for an API reference section.
Again, I refer you to JavaScript: The Definitive Guide, or to on-
line JavaScript references such as the excellent Mozilla Devel-
oper Network at http://developer.mozilla.org/.
The examples in this book can be downloaded from the book’s
web page, which will also include errata if any errors are dis-
covered after publication:
http://shop.oreilly.com/product/0636920011460.do
viii | Preface