Secrets of the JavaScript Ninja

PART 1 PREPARING FOR TRAINING . ...............................1
1 Enter the ninja 3
1.1 The JavaScript libraries we'll be tapping 4
1.2 Understanding the JavaScript language 5
1.3 Cross-browser considerations 6
1.4 Current best practices 9
Current best practice: testing 9 ■ Current best practice:
performance analysis 10
1.5 Summary 11
2 Arming with testing and debugging 13
2.1 Debugging code 14
Logging 14 ■ Breakpoints 16
vi CONTENTS
2.2 Test generation 17
2.3 Testing frameworks 19
QUnit 21 ■ YUI Test 22 ■ JsUnit 22
Newer unit-testing frameworks 22
2.4 The fundamentals of a test suite 22
The assertion 23 ■ Test groups 24 ■ Asynchronous testing 25
2.5 Summary 27
PART 2 APPRENTICE TRAINING.....................................29
3 Functions are fundamental 31
3.1 What's with the functional difference? 32
Why is JavaScript's functional nature important? 33
Sorting with a comparator 37
3.2 Declarations 40
Scoping and functions 43
3.3 Invocations 46
From arguments to function parameters 47 ■ Invocation as
a function 49 ■ Invocation as a method 50 ■ Invocation as
a constructor 52 ■ Invocation with the apply() and
call() methods 54
3.4 Summary 58
4 Wielding functions 61
4.1 Anonymous functions 62
4.2 Recursion 64
Recursion in named functions 64 ■ Recursion with methods 65
The pilfered reference problem 66 ■ Inline named functions 68
The callee property 70
4.3 Fun with function as objects 71
Storing functions 72 ■ Self-memoizing functions 73
Faking array methods 76
4.4 Variable-length argument lists 77
Using apply() to supply variable arguments 77
Function overloading 79
4.5 Checking for functions 86
4.6 Summary 88


CONTENTS vii
5 Closing in on closures 89
5.1 How closures work 90
5.2 Putting closures to work 94
Private variables 94 ■ Callbacks and timers 96
5.3 Binding function contexts 99
5.4 Partially applying functions 103
5.5 Overriding function behavior 106
Memoization 106 ■ Function wrapping 109
5.6 Immediate functions 111
Temporary scope and private variables 112 ■ Loops 115
Library wrapping 117
5.7 Summary 118
6 Object-orientation with prototypes 119
6.1 Instantiation and prototypes 120
Object instantiation 120 ■ Object typing via constructors 127
Inheritance and the prototype chain 128
HTML DOM prototypes 133
6.2 The gotchas! 135
Extending Object 135 ■ Extending Number 136
Subclassing native objects 137 ■ Instantiation issues 139
6.3 Writing class-like code 143
Checking for function serializability 146 ■ Initialization
of subclasses 147 ■ Preserving super-methods 148
6.4 Summary 150
7 Wrangling regular expressions 151
7.1 Why regular expressions rock 152
7.2 A regular expression refresher 153
Regular expressions explained 153 ■ Terms and operators 154
7.3 Compiling regular expressions 158
7.4 Capturing matching segments 161
Performing simple captures 161 ■ Matching using
global expressions 162 ■ Referencing captures 163
Non-capturing groups 165
7.5 Replacing using functions 166


viii CONTENTS
7.6 Solving common problems with regular expressions 168
Trimming a string 168 ■ Matching newlines 170
Unicode 171 ■ Escaped characters 172
7.7 Summary 172
8 Taming threads and timers 175
8.1 How timers and threading work 176
Setting and clearing timers 176 ■ Timer execution within
the execution thread 177 ■ Differences between timeouts
and intervals 179
8.2 Minimum timer delay and reliability 180
8.3 Dealing with computationally expensive processing 183
8.4 Central timer control 186
8.5 Asynchronous testing 189
8.6 Summary 190
PART 3 NINJA TRAINING ............................................191
9 Ninja alchemy: runtime code evaluation 193
9.1 Code evaluation mechanisms 194
Evaluation with the eval() method 194 ■ Evaluation via the
Function constructor 197 ■ Evaluation with timers 197
Evaluation in the global scope 198 ■ Safe code evaluation 199
9.2 Function "decompilation" 201
9.3 Code evaluation in action 204
Converting JSON 204 ■ Importing namespaced code 205
JavaScript compression and obfuscation 206 ■ Dynamic
code rewriting 208 ■ Aspect-oriented script tags 209
Metalanguages and DSLs 210
9.4 Summary 213
10 With statements 215
10.1 What's with "with"? 216
Referencing properties within a with scope 216 ■ Assignments
within a with scope 218 ■ Performance considerations 219
10.2 Real-world examples 221
10.3 Importing namespaced code 223


CONTENTS ix
10.4 Testing 223
10.5 Templating with "with" 224
10.6 Summary 227
11 Developing cross-browser strategies 229
11.1 Choosing which browsers to support 230
11.2 The five major development concerns 231
Browser bugs and differences 232 ■ Browser bug fixes 233
Living with external code and markup 234
Missing features 239 ■ Regressions 240
11.3 Implementation strategies 242
Safe cross-browser fixes 242 ■ Object detection 243
Feature simulation 245 ■ Untestable browser issues 247
11.4 Reducing assumptions 249
11.5 Summary 251
12 Cutting through attributes, properties, and CSS 253
12.1 DOM attributes and properties 255
Cross-browser naming 256 ■ Naming restrictions 257
Differences between XML and HTML 257 ■ Behavior of
custom attributes 258 ■ Performance considerations 258
12.2 Cross-browser attribute issues 262
DOM id/name expansion 262 ■ URL normalization 264
The style attribute 265 ■ The type attribute 265
The tab index problem 266 ■ Node names 267
12.3 Styling attribute headaches 267
Where are my styles? 268 ■ Style property naming 270
The float style property 271 ■ Conversion of pixel values 271
Measuring heights and widths 272 ■ Seeing through
opacity 276 ■ Riding the color wheel 279
12.4 Fetching computed styles 282
12.5 Summary 285
PART 4 MASTER TRAINING.........................................287
13 Surviving events 289
13.1 Binding and unbinding event handlers 290
13.2 The Event object 294


x CONTENTS
13.3 Handler management 297
Centrally storing associated information 298
Managing event handlers 300
13.4 Triggering events 309
Custom events 310
13.5 Bubbling and delegation 315
Delegating events to an ancestor 315 ■ Working around
browser deficiencies 316
13.6 The document ready event 324
13.7 Summary 326
14 Manipulating the DOM 329
14.1 Injecting HTML into the DOM 330
Converting HTML to DOM 331 ■ Inserting into
the document 334 ■ Script execution 336
14.2 Cloning elements 338
14.3 Removing elements 340
14.4 Text contents 341
Setting text 342 ■ Getting text 343
14.5 Summary 344
15 CSS selector engines 345
15.1 The W3C Selectors API 347
15.2 Using XPath to find elements 349
15.3 The pure-DOM implementation 351
Parsing the selector 353 ■ Finding the elements 354
Filtering the set 355 ■ Recursing and merging 356
Bottom-up selector engine 357
15.4 Summary 359