JavaScript Enlightenment [Lindley 2013-01-10].pdf

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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
JavaScript Enlightenment
Cody Lindley
First Edition, based on JavaScript 1.5, ECMA-262, Edition 3
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Table of Contents
About the Author
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8
About the Technical Editors
..................................................................................................................
9
Michael Richardson
................................................................................................................................
9
Kyle Simpson
.........................................................................................................................................
9
Nathan Smith
........................................................................................................................................
9
Ben Nadel
..............................................................................................................................................
9
Ryan Florence
........................................................................................................................................
10
Nathan Logan
........................................................................................................................................
10
Introduction
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11
Why did I write this book?
......................................................................................................................
11
Who should read this book?
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12
Why JavaScript 1.5 & ECMA-262 Edition 3?
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12
Why didn't I cover the Date(), Error(), RegEx() objects?
...........................................................................
12
Preface
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13
More code, less words
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13
Exhaustive code and repetition
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13
Color-coding Conventions
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13
jsFiddle, JS Bin, and Firebug lite-dev
.......................................................................................................
14
Chapter 1 - JavaScript Objects
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15
Creating objects
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15
JavaScript constructors construct and return object instances
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20
The JavaScript native/built-in object constructors
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21
User-defined/non-native object constructor functions
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Instantiating constructors using the new operator
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24
Creating shorthand/literal values from constructors
..................................................................................
25
Primitive (aka simple) values
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27
The primitive values null, undefined, "string", 10, true, and false are not objects
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28
How primitive values are stored/copied in JavaScript
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Primitive values are equal by value
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The string, number, and boolean primitive values act like objects when used like objects
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31
Complex (aka composite) values
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How complex values are stored/copied in JavaScript
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Complex objects are equal by reference
..................................................................................................
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Complex objects have dynamic properties
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The typeof operator used on primitive and complex values
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35
Dynamic Properties allow for mutable objects
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36
All constructor instances have constructor properties that point to their constructor function
.......................
37
Verify that an object is an instance of a particular constructor function
......................................................
39
..
The semantics between "JavaScript objects" vs. "Object() objects"
............................................................
42
Chapter 2 - Working with Objects and Properties
...............................................................................
43
Complex objects can contain most of the JavaScript values as properties
...................................................
43
Encapsulating complex objects in a programmatically beneficial way
.........................................................
44
Getting/setting/updating an object's properties using dot notation or bracket notation
................................
45
Deleting object properties
.......................................................................................................................
48
How references to object properties are resolved
.....................................................................................
48
Using hasOwnProperty, verify that an object property is not from the prototype chain
.................................
51
Checking if an object contains a given property using the in operator
........................................................
51
Enumerate (loop over) an object’s properties using the for in loop
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52
Host objects vs. native objects
................................................................................................................
53
Enhancing & extending objects with Underscore.js
...................................................................................
54
Chapter 3 - Object()
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57
Conceptual overview of using Object() objects
.........................................................................................
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Object() parameters
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58
Object() properties and methods
.............................................................................................................
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Object() object instance properties and methods
.....................................................................................
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Creating Object() objects using "object literals"
........................................................................................
59
All objects inherit from Object.prototype
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61
Chapter 4 - Function()
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Conceptual overview of using Function() objects
......................................................................................
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Function() parameters
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Function() properties and methods
..........................................................................................................
64
Function object instance properties and methods
.....................................................................................
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Functions always return a value
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Functions are first-class citizens (not just syntax, but values)
....................................................................
66
Passing parameters to a function
.............................................................................................................
67
this & arguments values available to all functions
.....................................................................................
67
The arguments.callee property
...............................................................................................................
68
The function instance length property & arguments.length
.......................................................................
69
Redefining function parameters
...............................................................................................................
70
Return a function before it is done (i.e. cancel function execution)
............................................................
70
Defining a function (statement, expression, or constructor)
.......................................................................
71
Invoking a function (function, method, constructor, or call() & apply())
......................................................
72
Anonymous functions
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73
Self-invoking function expression
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Self-invoking anonymous function statements
..........................................................................................
74
Functions can be nested
.........................................................................................................................
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Passing functions to functions & returning functions from functions
...........................................................
75
Invoking function statements before they are defined (aka function hoisting)
.............................................
76
A function can call itself (aka recursion)
...................................................................................................
77
Chapter 5 - The Head/Global Object
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78
Conceptual overview of the head object
...................................................................................................
78
Global functions contained within the head object
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79
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The head object vs. global properties and global variables
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Referring to the head object
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The head object is implied and typically not referenced explicitly
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Chapter 6 - The this Keyword
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Conceptual overview of this and how it refers to objects
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How is the value of this determined?
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The this keyword refers to the head object in nested functions
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Working around the nested function issue by leveraging the scope chain
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Controlling the value of this using call() or apply()
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Using the this keyword inside a user-defined constructor function
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The keyword this inside a prototype method refers to a constructor instance
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Chapter 7 - Scope & Closures
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Conceptual overview of JavaScript scope
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JavaScript does not have block scope
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Use var inside of functions to declare variables and avoid scope gotchas
....................................................
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The scope chain (aka lexical scoping)
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The scope chain lookup returns the first found value
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Scope is determined during function definition, not invocation
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Closures are caused by the scope chain
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Chapter 8 - Function Prototype Property
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Conceptual overview of the prototype chain
.............................................................................................
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Why care about the prototype property?
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Prototype is standard on all Function() instances
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The default prototype property is an Object() object
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Instances created from a constructor function are linked to the constructor’s prototype property
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Last stop in the prototype chain is Object.prototype
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The prototype chain returns the first property match it finds in the chain
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Replacing the prototype property with a new object removes the default constructor property
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Instances that inherit properties from prototype will always get the latest values
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