JavaScript_Succinctly

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Notes An unlimited number of function and eval scopes can be created, while only one global scope is used by a JavaScript environment. The global scope is the last stop in the scope chain. Functions that contain functions create stacked execution scopes. These stacks, which are chained together, are often referred to as the scope chain. JavaScript does not have block scope Since logic statements (e.g., if) and looping statements (e.g., for) do not create a scope, variables can overwrite each other. Examine the following code and make sure you understand that the value of foo is being redefined as the program executes the code. Sample: sample111.html var foo = 1; // foo = 1. if (true) { foo = 2; // foo = 2. for (var i = 3; i
Sample: sample112.html var foo = function () { var boo = function () { bar = 2; // No var used, so bar is placed in the global scope at window.bar } (); } (); console.log(bar); // Logs 2, because bar is in the global scope. // As opposed to... var foo = function () { var boo = function () { var doo = 2; } (); } (); // console.log(doo); logs undefined. doo is in the boo function scope, so an error occurs The concept to take away here is that you should always use var when defining variables inside of a function. This will prevent you from dealing with potentially confusing scope problems. The exception to this convention, of course, is when you want to create or change properties in the global scope from within a function. The scope chain (aka lexical scoping) There is a lookup chain that is followed when JavaScript looks for the value associated with a variable. This chain is based on the hierarchy of scope. In the code that follows, I am logging the value of sayHiText from the func2 function scope. Sample: sample113.html var sayHiText = 'howdy'; var func1 = function () { var func2 = function () { console.log(sayHiText); // func2 scope, but it finds sayHiText in global scope. } (); 115
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By Cody Lindley Foreword by Daniel
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Table of Contents About the Author
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Object() object instance properties
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The Story behind the Succinctly Ser
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About the Author Cody Lindley is a
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Advanced technical books written ab
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“Consider that the cody object cr
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Chapter 1 JavaScript Objects Creati
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Using JavaScript, the getGender met
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* The String() constructor function
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new object that is returned from th
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Notes The Math object is the oddbal
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In this snippet, we created a new s
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Verify that literals are created fr
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The primitive values null, undefine
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The concept to take away here is th
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* This will throw an error and not
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copied, but not the actual value. T
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Sample: sample21.html // Primitive
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Notes Careful! If you mutate the na
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console.log(instanceOfCustomObject.
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myObject.prop = 'test'; myArray.pro
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Chapter 2 Working with Objects and
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Sample: sample31.html // Encapsula
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cody['getGender']() // Just slap th
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een defined. You might think that b
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console.log(myArray.toLocaleString(
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Sample: sample44.html var cody = {
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Sometimes a web browser manufacture
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I like this library because it take
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console.log(stringObject); // Logs
Page 64 and 65: Chapter 4 Number() Conceptual overv
Page 66 and 67: NEGATIVE_INFINITY POSITIVE_INFINIT
Page 68 and 69: Parameter passed to Boolean() = Mat
Page 70 and 71: console.log(Boolean(Math)); console
Page 72 and 73: var numberObject = new Number(1.100
Page 74 and 75: Chapter 7 Null Conceptual overview
Page 76 and 77: Chapter 8 Undefined Conceptual over
Page 78 and 79: Chapter 9 The Head/Global Object Co
Page 80 and 81: object. } // Logs bar, foo's value
Page 82 and 83: Make sure you understand that the h
Page 84 and 85: Object() parameters The Object() co
Page 86 and 87: Sample: sample72.html var cody = n
Page 88 and 89: Logs 'foo', being found at Object.p
Page 90 and 91: Sample: sample77.html var addFunct
Page 92 and 93: Sample: sample79.html var yelp = f
Page 94 and 95: parameters when defining the functi
Page 96 and 97: Notes The arguments.length property
Page 98 and 99: Invoking a function (function, meth
Page 100 and 101: Self-invoking anonymous function st
Page 102 and 103: the bar variable. All this is to sh
Page 104 and 105: Chapter 12 The this Keyword Concept
Page 106 and 107: Clearly, the value of this is based
Page 108 and 109: Working around the nested function
Page 110 and 111: What you need to learn here is that
Page 112 and 113: var john = new Person(); // No argu
Page 116 and 117: } (); How is the value of sayHiTex
Page 118 and 119: var parentFunction = function () {
Page 120 and 121: Chapter 14 Function Prototype Prope
Page 122 and 123: Sample: sample119.html var myFunct
Page 124 and 125: In this example, the foo property i
Page 126 and 127: console.log(FooInstance.constructor
Page 128 and 129: Providing a new object as the proto
Page 130 and 131: var chuck = new Person(0, 0); conso
Page 132 and 133: An Array() is just a special type o
Page 134 and 135: It is more common to see an array d
Page 136 and 137: console.log(myArray.length); // Log
Page 138 and 139: while (myArrayLength--) { // If len
Page 140 and 141: ceil() cos() exp() floor() log() ma
Page 142 and 143: That is: a complex value is equal t
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JavaScript_Succinctly

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