Ajax The Complete Reference

674 Pages·2008·18.56 MB·English

by  Thomas Powell

Ajax: The Complete Reference
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About the Author
Thomas A. Powell ([email protected]) has been
involved in the Internet community for almost
20 years. In the early 1990s he worked for the first
Internet service provider in Southern California,
CERFnet. In 1994 he founded PINT, Inc. (pint.com)
a Web development firm with headquarters in San
Diego, which today services a diverse range of
educational and corporate clients around the country.
He is also the lead investor and founder of port80
Software (port80software.com), which sells Web
server and development products to thousands of
organizations around the world.
In addition, Powell is the author of numerous
other Web development books, including the
bestsellers JavaScript: The Complete Reference, HTML &
XHTML: The Complete Reference, Web Design: The
Complete Reference, and Web Site Engineering. He also
writes frequently about Web technologies for Network
World magazine.
Mr. Powell teaches Web design and development
classes for the University of California, San Diego
Computer Science and Engineering Department as
well as for the Information Technologies program at
the UCSD Extension. He holds a B.S. from UCLA and
an M.S. in Computer Science from UCSD.
About the Technical Editor
Ric Smith is a principal product manager for Oracle’s
Application Development Tools. He is responsible for
the evangelism and product direction of Oracle ADF
Faces Rich Client as well as Oracle’s Ajax and Java EE
Web Tier offerings. Prior to joining Oracle’s Fusion
Middleware team, Ric worked for Oracle’s consulting
business as a principal consultant, specializing in Java
EE and Ajax development. In addition, Ric is a
frequent speaker at industry events and has written
articles featured in industry publications such as Java
Developer’s Journal and Ajax World magazine. He is
also a member of the OpenAjax Alliance and
a graduate of the University of Arizona.
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Ajax: The Complete Reference
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DOI: 10.1036/007149216X
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Contents at a Glance
Part I Core Ideas
1 Introduction to Ajax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pre-Ajax JavaScript Communications Techniques . . . . . . . . . . . . . . . . . . . . 15
3 XMLHttpRequest Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4 Data Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Part II Applied Ajax
5 Developing an Ajax Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
6 Networking Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
7 Security Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
8 User Interface Design for Ajax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
9 Site and Application Architecture with Ajax . . . . . . . . . . . . . . . . . . . . . . . . 407
Part III Advanced Topics
10 Web Services and Beyond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 483
Part IV Appendixes
A JavaScript Quick Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 551
B HTTP 1.1 Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 587
C AjaxTCR Library Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 609
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 635
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Contents
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
Part I Core Ideas
1 Introduction to Ajax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Ajax Defi ned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Hello Ajax World . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
The Challenges of Running Ajax Examples Locally . . . . . . . . . . . . . . 11
The Rise of Ajax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Implications of Ajax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2 Pre-Ajax JavaScript Communications Techniques . . . . . . . . . . . . . . . . . . . . 15
One-way Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
One-way Image Object Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
One-way Iframes with Query Strings . . . . . . . . . . . . . . . . . . . . . . . . . . 22
One-way Script Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Other Approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
One-way Iframes with Form Posts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Cookie-based Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Two-way Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Images for Two-way Communications . . . . . . . . . . . . . . . . . . . . . . . . 32
Two-way Script Tag Communication . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Less Common Two-way Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Two-way Iframes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Communications Pattern Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Example Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
A Client-Side JS Error Reporter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Offsite Link Press Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Fancy Ratings—Pre-Ajax Version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
RSS Reader . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
3 XMLHttpRequest Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Overview of XHRs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Instantiation and Cross-Browser Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
ActiveX XHR Anxiety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
A Cross-Browser XHR Wrapper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
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viii Ajax: The Complete Reference
XHR Request Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Synchronous Requests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Asynchronous Requests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Sending Data via GET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Sending Data via Post . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Request Headers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Other HTTP Requests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Head Requests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Response Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
readyState Revisited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
status and statusText . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
responseText . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
responseXML . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Response Headers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Controlling Requests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Authentication with XHRs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Propriety and Emerging XHR Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Managing MIME Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Multipart Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
onProgress and Partial Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Other Firefox Event Handlers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
XHR Arcana and Future Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
XHR Implications and Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Ajax and Memory Leaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
4 Data Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Ajax and Character Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Data Format Decisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Encoding/Decoding Requests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Encoding/Decoding Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Security Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Transmission Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Standard Encoding: x-www-form-urlencoded . . . . . . . . . . . . . . . . . . . . . . . . 121
Extending Standard Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Form Serialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Object Serialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Using Other Input Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
XML . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
JSON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Other Request Forms: YAML, Text, and Beyond . . . . . . . . . . . . . . . . . 136
File Attachments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Response Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Text Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Script Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
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