JavaScript programming for the absolute beginner: the fun way to learn programming

368 Pages·2001·13.14 MB·English

by  Andy Harris

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Team-Fly®
JavaScript
Programming
ANDY HARRIS
© 2001 by Prima Publishing. All rights reserved. No part of this Publisher:
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out written permission from Prima Publishing, except for the
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Series Editor:
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Andy Harris
marks of Prima Communications, Inc. PRIMA TECH
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trademarks or registered trademarks of Microsoft Corporation Melody Layne and Kim Spilker
in the U.S. and other countries.
Technical Reviewer:
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registered trademarks of Netscape Communications Corpora-
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To Heather, Elizabeth, and Matthew
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A k o e g e s
c n wl d m nt
I
first acknowledge Him from whom all flows.
Thank you again, Heather, for listening to the keyboard clicking all those
late nights. You are the sun and the stars to me.
Thanks to Melody Layne for being a good friend and a good editor (at the same time, even!).
Thank you to Kim Spilker for your encouragement on this project, and to all the folks
at Prima for being nice people to work with.
A special thank you to Andy Saff for copyediting. If this book makes any sense at all, it’s
because of you.
Thank you also to Michael Vine for technical editing. I appreciate your efforts very much.
A very special thank you goes to Scott Porter for his excellent game development library.
His clever programming and selfless generosity make JavaScript game programming
much more accessible than it has ever been before.
I especially want to thank all my students, present and past. You have taught me so
much more than I was ever able to teach you.
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A o t t A t o
b u he u h r
A
ndy Harris began his teaching career as a high school special education
teacher. During that time, he taught himself enough computing to do part-time
computer consulting and database work. He began teaching computing at
the university level in the late 1980s as a part-time job. Since 1995, he has
been a full-time lecturer in the Computer Science Department of Indiana University/
Purdue University—Indianapolis. He manages the IUPUI Streaming Media Lab for the
department and teaches classes in several programming languages. His main interests
are Java, Visual Basic, Perl, JavaScript/dynamic HTML, virtual reality, programming on
portable devices, and streaming media.
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C t n s a a
on e t t
G n e
la c
CHAPTER 1 Variables, Input, and Output 1
CHAPTER 2 The Fortune Teller:
Random Numbers and the if Statement 21
CHAPTER 3 The Number Guesser: for and while Loops 45
CHAPTER 4 The Basic Mad Lib Program and
Object-Based Programming 63
CHAPTER 5 Advanced Mad Lib: Using
the Other Form Elements 89
CHAPTER 6 Petals around theRose: Dynamic Output 115
CHAPTER 7 Image Swapping and Lookup Tables:
The Basketball Game 139
CHAPTER 8 Dynamic HTML: The Stealth Submarine 171
CHAPTER 9 Sprite Animation: The Racer 203
CHAPTER 10 Using Other gameLib Features:
The Dogfight Game 235
CHAPTER 11 Cookies and the Mouse: The Jigsaw Puzzle 261
CHAPTER 12 The Game Creation Process: The Brick Game 289
APPENDIX A Syntax Reference 321
Index 335
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C t n s
on e t
Introduction ................................................................................xiii
1
CHAPTER Variables, Input, and Output 1
The Project: Name Game .............................................................2
Adding Code to HTML ..................................................................3
Using Variables..............................................................................5
Getting Input from the User.........................................................8
Building More Complicated Text ...............................................10
Working with Numbers...............................................................11
Using String Methods.................................................................16
Summary .....................................................................................19
2
CHAPTER The Fortune Teller:
Random Numbers and
the if Statement 21
The Project: The Fortune Teller..................................................22
Getting Random Numbers .........................................................22
Making Specialized Random Numbers.....................................24
Making Decisions with the if Statement ...................................28
Using the else Structure.............................................................32
Using Nested if Structures .........................................................34
Using the switch Structure.........................................................38
Returning to the Fortune Program ............................................42
Summary .....................................................................................44
3
CHAPTER The Number Guesser:
for and while Loops 45
The Project: The Number Guesser ............................................46
Counting Forward .......................................................................46
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viii Skipping Values...........................................................................50
Counting Backward.....................................................................52
s
t Using the while Loop..................................................................53
n
e
Returning to the Number Guesser ............................................57
t
n
o Summary .....................................................................................62
C
4
CHAPTER The Basic Mad Lib Program
and Object-Based
Programming 63
The Project: Mad Lib...................................................................64
Objects and HTML.......................................................................65
Reading the Properties of an Object..........................................68
Methods.......................................................................................71
Events...........................................................................................74
The Purpose of Functions...........................................................78
Event-Driven Input and Output..................................................79
Back to the Mad Lib Program.....................................................84
Summary .....................................................................................88
5
CHAPTER Advanced Mad Lib:
Using the Other Form Elements 89
The Project: the Advanced Mad Lib...........................................90
Working with Textlike Objects....................................................90
Using Check Boxes .....................................................................93
Using Radio Buttons...................................................................97
Using the select Object.............................................................102
Using Multiline Select Boxes ...................................................105
Returning to the Advanced Mad Lib Program........................107
Summary ...................................................................................114
6
CHAPTER Petals around the Rose:
Dynamic Output 115
The Project: Petals around the Rose........................................116
Generating Output in Frames ..................................................118
Displaying Output in Separate Windows................................122
Designing the Petals around the Rose Game.........................127
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Creating Graphics for JavaScript Games................................129 ix
Generating the Dice-Rolling Routine.......................................133
C
Summary ...................................................................................137 o
n
t
e
7
n
t
CHAPTER Image Swapping and Lookup s
Tables: The Basketball Game 139
The Project: The Basketball Game...........................................140
Swapping Images .....................................................................141
Using the MouseOver Events ..................................................145
Creating Simple Arrays ............................................................149
Creating Arrays with Images....................................................152
Using Lookup Tables.................................................................155
Putting Together the Basketball Game....................................160
Summary ...................................................................................168
8
CHAPTER Dynamic HTML: The Stealth
Submarine 171
The Project: The Stealth Submarine Program........................172
Dealing with Browser Dependency .........................................173
Using Cascading Style Sheets .................................................176
Working with Positionable CSS Elements ..............................179
Changing the Text in a Positionable Element.........................185
Adding Cross-Platform Sound.................................................189
Putting It Together in the Stealth Sub Game..........................192
Summary ...................................................................................200
9
CHAPTER Sprite Animation: The Racer 203
The Project: The Racer Program..............................................204
Introducing the Sprite...............................................................206
Moving Sprites Around ............................................................211
Using Frame Animation in Sprites ..........................................214
Detecting Collision....................................................................218
Creating a Race Timer...............................................................221
Returning to the Racer Program..............................................224
Summary ...................................................................................233
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