Speaking JavaScript. An In-Depth Guide for Programmers

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• Speaking JavaScript
• Dedication
• Preface
  • What You Need to Know About This Book
  • Tips for Reading This Book
    • The Four Parts of This Book
    • JavaScript Command Lines
    • Notational Conventions
      • Describing syntax
      • Referring to methods
      • Command-line interaction
      • Tips, notes, and warnings
    • Quickly Finding Documentation
  • Safari Books Online
  • How to Contact Us
  • Acknowledgments
    • Preparing for JavaScript
    • Help with JavaScript
    • Reviewers
• I. JavaScript Quick Start
  • 1. Basic JavaScript
    • Background
      • JavaScript Versus ECMAScript
      • Influences and Nature of the Language
    • Syntax
      • An Overview of the Syntax
      • Statements Versus Expressions
      • Semicolons
      • Comments
    • Variables and Assignment
      • Assignment
      • Compound Assignment Operators
      • Identifiers and Variable Names
    • Values
      • Primitive Values Versus Objects
      • Primitive Values
      • Objects
      • undefined and null
        • Checking for undefined or null
      • Categorizing Values Using typeof and instanceof
    • Booleans
      • Truthy and Falsy
      • Binary Logical Operators
      • Equality Operators
    • Numbers
    • Operators
    • Strings
      • String Operators
      • String Methods
    • Statements
      • Conditionals
      • Loops
    • Functions
      • Function Declarations Are Hoisted
      • The Special Variable arguments
      • Too Many or Too Few Arguments
      • Optional Parameters
      • Enforcing an Arity
      • Converting arguments to an Array
    • Exception Handling
    • Strict Mode
    • Variable Scoping and Closures
      • Variables Are Function-Scoped
      • Variables Are Hoisted
      • Closures
      • The IIFE Pattern: Introducing a New Scope
        • IIFE use case: inadvertent sharing via closures
    • Objects and Constructors
      • Single Objects
      • Arbitrary Property Keys
      • Extracting Methods
      • Functions Inside a Method
      • Constructors: Factories for Objects
    • Arrays
      • Array Literals
      • Array Methods
      • Iterating over Arrays
    • Regular Expressions
      • Method test(): Is There a Match?
      • Method exec(): Match and Capture Groups
      • Method replace(): Search and Replace
    • Math
    • Other Functionality of the Standard Library
• II. Background
  • 2. Why JavaScript?
    • Is JavaScript Freely Available?
    • Is JavaScript Elegant?
    • Is JavaScript Useful?
      • Graphical User Interfaces
      • Other Technologies Complementing JavaScript
    • Does JavaScript Have Good Tools?
    • Is JavaScript Fast Enough?
    • Is JavaScript Widely Used?
    • Does JavaScript Have a Future?
    • Conclusion
  • 3. The Nature of JavaScript
    • Quirks and Unorthodox Features
    • Elegant Parts
    • Influences
  • 4. How JavaScript Was Created
  • 5. Standardization: ECMAScript
  • 6. Historical JavaScript Milestones
• III. JavaScript in Depth
  • 7. JavaScripts Syntax
    • An Overview of the Syntax
    • Comments
    • Expressions Versus Statements
      • Expressions
      • Statements
        • Conditional statement versus conditional expressions
        • Using ambiguous expressions as statements
        • Evaluating an object literal via eval()
        • Immediately invoking a function expression
    • Control Flow Statements and Blocks
    • Rules for Using Semicolons
      • No Semicolon After a Statement Ending with a Block
      • The Empty Statement
      • Automatic Semicolon Insertion
        • Example: ASI via illegal token
        • Example: ASI via closing brace
        • Pitfall: ASI can unexpectedly break up statements
        • Pitfall: ASI might unexpectedly not be triggered
    • Legal Identifiers
    • Invoking Methods on Number Literals
    • Strict Mode
      • Switching on Strict Mode
      • Strict Mode: Recommended, with Caveats
      • Variables Must Be Declared in Strict Mode
      • Functions in Strict Mode
        • Functions must be declared at the top level of a scope
        • Stricter rules for function parameters
        • The arguments objects has fewer properties
        • this is undefined in nonmethod functions
      • Setting and Deleting Immutable Properties Fails with an Exception in Strict Mode
      • Unqualified Identifiers Cant Be Deleted in Strict Mode
      • eval() Is Cleaner in Strict Mode
      • Features That Are Forbidden in Strict Mode
  • 8. Values
    • JavaScripts Type System
      • JavaScripts Types
      • Static Versus Dynamic
      • Static Typing Versus Dynamic Typing
      • Static Type Checking Versus Dynamic Type Checking
      • Coercion
    • Primitive Values Versus Objects
    • Primitive Values
    • Objects
    • undefined and null
      • Occurrences of undefined and null
        • Occurrences of undefined
        • Occurrences of null
      • Checking for undefined or null
        • Checking for null
        • Checking for undefined
        • Checking for either undefined or null
      • The History of undefined and null
      • Changing undefined
    • Wrapper Objects for Primitives
      • Wrapper Objects Are Different from Primitives
      • Wrapping and Unwrapping Primitives
      • Primitives Borrow Their Methods from Wrappers
    • Type Coercion
      • Type Coercion Can Hide Bugs
      • Functions for Converting to Boolean, Number, String, and Object
      • Algorithm: ToPrimitive()Converting a Value to a Primitive
        • Examples: ToPrimitive() in action
  • 9. Operators
    • Operators and Objects
    • Assignment Operators
      • Compound Assignment Operators
    • Equality Operators: === Versus ==
      • Strict Equality (===, !==)
        • Pitfall: NaN
        • Strict inequality (!==)
      • Normal (Lenient) Equality (==, !=)
        • Lenient inequality (!=)
        • Pitfall: lenient equality is different from conversion to boolean
        • Pitfall: lenient equality and strings
        • Pitfall: lenient equality and objects
      • There Are No Valid Use Cases for ==
        • Use case: checking for undefined or null
        • Use case: working with numbers in strings
        • Use case: comparing wrapper instances with primitives
    • Ordering Operators
      • The Algorithm
    • The Plus Operator (+)
      • The Algorithm
    • Operators for Booleans and Numbers
    • Special Operators
      • The Conditional Operator ( ? : )
      • The Comma Operator
      • The void Operator
        • What is void used for?
        • Why does JavaScript have a void operator?
    • Categorizing Values via typeof and instanceof
      • typeof: Categorizing Primitives
        • Pitfall: typeof null
        • The history of typeof null
        • Checking whether a variable exists
      • instanceof: Checking Whether an Object Is an Instance of a Given Constructor
    • Object Operators
  • 10. Booleans
    • Converting to Boolean
      • Manually Converting to Boolean
      • Truthy and Falsy Values
        • Pitfall: all objects are truthy
        • History: Why are objects always truthy?
    • Logical Operators
      • Binary Logical Operators: And (&&) and Or (||)
      • Logical And (&&)
      • Logical Or (||)
        • Pattern: providing a default value
        • Example 1: a default for a parameter
        • Example 2: a default for a property
        • Example 3: a default for the result of a function
      • Logical Not (!)
    • Equality Operators, Ordering Operators
    • The Function Boolean
  • 11. Numbers
    • Number Literals
      • Exponent
      • Invoking Methods on Literals
    • Converting to Number
      • Manually Converting to Number
      • parseFloat()
    • Special Number Values
      • NaN
        • Pitfall: checking whether a value is NaN
      • Infinity
        • Error: a numbers magnitude is too large
        • Error: division by zero
        • Computing with Infinity
        • Checking for Infinity
      • Two Zeros
        • Best practice: pretend theres only one zero
        • Distinguishing the two zeros
    • The Internal Representation of Numbers
      • Special Exponents
    • Handling Rounding Errors
    • Integers in JavaScript
      • Ranges of Integers
      • Representing Integers as Floating-Point Numbers
        • Best practice
      • Safe Integers
        • Definitions in ECMAScript 6
        • Safe results of arithmetic computations
    • Converting to Integer
      • Integers via Math.floor(), Math.ceil(), and Math.round()
      • Integers via the Custom Function ToInteger()
      • 32-bit Integers via Bitwise Operators
        • Bitwise Or (|)
        • Shift operators
        • Should I use bitwise operators to coerce to integer?
      • Integers via parseInt()
        • The radix
        • Explanation
        • Summary
    • Arithmetic Operators
    • Bitwise Operators
      • Background Knowledge
        • Binary complements
        • Signed 32-bit integers
        • Inputting and outputting binary numbers
      • Bitwise Not Operator
      • Binary Bitwise Operators
      • Bitwise Shift Operators
    • The Function Number
    • Number Constructor Properties
    • Number Prototype Methods
      • Number.prototype.toFixed(fractionDigits?)
      • Number.prototype.toPrecision(precision?)
      • Number.prototype.toString(radix?)
        • Decimal exponential notation
      • Number.prototype.toExponential(fractionDigits?)
    • Functions for Numbers
    • Sources for This Chapter
  • 12. Strings
    • String Literals
    • Escaping in String Literals
    • Character Access
    • Converting to String
      • Manually Converting to String
        • Pitfall: conversion is not invertible
    • Comparing Strings
    • Concatenating Strings
      • Concatenation: The Plus (+) Operator
      • Concatenation: Joining an Array of String Fragments
    • The Function String
    • String Constructor Method
    • String Instance Property length
    • String Prototype Methods
      • Extract Substrings
      • Transform
      • Search and Compare
      • Test, Match, and Replace with Regular Expressions
  • 13. Statements
    • Declaring and Assigning Variables
    • The Bodies of Loops and Conditionals
    • Loops
      • Mechanisms to Be Used with Loops
      • while
      • do-while
      • for
      • for-in
        • Best practice: dont use for-in for arrays
        • Best practice: be careful with for-in for objects
      • for each-in
    • Conditionals
      • if-then-else
        • Chaining if statements
        • Pitfall: dangling else
      • switch
    • The with Statement
      • Syntax and Semantics
      • The with Statement Is Deprecated
        • Techniques for avoiding the with statement
      • The Rationale for the Deprecation
    • The debugger Statement
  • 14. Exception Handling
    • What Is Exception Handling?
    • Exception Handling in JavaScript
      • throw
      • try-catch-finally
      • Examples
    • Error Constructors
    • Stack Traces
    • Implementing Your Own Error Constructor
  • 15. Functions
    • The Three Roles of Functions in JavaScript
    • Terminology: Parameter Versus Argument
    • Defining Functions
      • Function Expressions
        • Named function expressions
      • Function Declarations
      • The Function Constructor
    • Hoisting
    • The Name of a Function
    • Which Is Better: A Function Declaration or a Function Expression?
    • More Control over Function Calls: call(), apply(), and bind()
      • func.apply(thisValue, argArray)
      • func.bind(thisValue, arg1, ..., argN)
    • Handling Missing or Extra Parameters
      • All Parameters by Index: The Special Variable arguments
        • Deprecated features of arguments
      • Mandatory Parameters, Enforcing a Minimum Arity
      • Optional Parameters
      • Simulating Pass-by-Reference Parameters
      • Pitfall: Unexpected Optional Parameters
    • Named Parameters
      • Named Parameters as Descriptions
      • Optional Named Parameters
      • Simulating Named Parameters in JavaScript
  • 16. Variables: Scopes, Environments, and Closures
    • Declaring a Variable
    • Background: Static Versus Dynamic
    • Background: The Scope of a Variable
    • Variables Are Function-Scoped
    • Variable Declarations Are Hoisted
    • Introducing a New Scope via an IIFE
      • IIFE Variation: Prefix Operators
      • IIFE Variation: Already Inside Expression Context
      • IIFE Variation: An IIFE with Parameters
      • IIFE Applications
    • Global Variables
      • Best Practice: Avoid Creating Global Variables
      • Module Systems Lead to Fewer Globals
    • The Global Object
      • Cross-Platform Considerations
      • Use Cases for window
        • Use case: marking global variables
        • Use case: built-ins
        • Use case: style checkers
        • Use case: checking whether a global variable exists
        • Use case: creating things in global scope
    • Environments: Managing Variables
    • Closures: Functions Stay Connected to Their Birth Scopes
      • Handling Closures via Environments
      • Pitfall: Inadvertently Sharing an Environment
  • 17. Objects and Inheritance
    • Layer 1: Single Objects
      • Kinds of Properties
      • Object Literals
      • Dot Operator (.): Accessing Properties via Fixed Keys
        • Getting properties
        • Calling methods
        • Setting properties
        • Deleting properties
        • The return value of delete
      • Unusual Property Keys
      • Bracket Operator ([]): Accessing Properties via Computed Keys
        • Getting properties via the bracket operator
        • Calling methods via the bracket operator
        • Setting properties via the bracket operator
        • Deleting properties via the bracket operator
    • Converting Any Value to an Object
    • this as an Implicit Parameter of Functions and Methods
      • Calling Functions While Setting this: call(), apply(), and bind()
        • Function.prototype.call(thisValue, arg1?, arg2?, ...)
        • Function.prototype.apply(thisValue, argArray)
        • Function.prototype.bind(thisValue, arg1?, ..., argN?)
      • apply() for Constructors
        • Manually simulating an apply() for constructors
        • A library method
        • An alternative approach
      • Pitfall: Losing this When Extracting a Method
        • How to get a warning
        • How to properly extract a method
        • Callbacks and extracted methods
      • Pitfall: Functions Inside Methods Shadow this
        • Workaround 1: that = this
        • Workaround 2: bind()
        • Workaround 3: a thisValue for forEach()
    • Layer 2: The Prototype Relationship Between Objects
      • Inheritance
      • Overriding
      • Sharing Data Between Objects via a Prototype
      • Getting and Setting the Prototype
        • Creating a new object with a given prototype
        • Reading the prototype of an object
        • Checking whether one object a prototype of another one
        • Finding the object where a property is defined
      • The Special Property __proto__
      • Setting and Deleting Affects Only Own Properties
        • Setting a property
        • Deleting an inherited property
        • Changing properties anywhere in the prototype chain
    • Iteration and Detection of Properties
      • Listing Own Property Keys
      • Listing All Property Keys
      • Checking Whether a Property Exists
      • Examples
        • The effects of enumerability
        • The effects of inheritance
        • Computing the number of own properties of an object
    • Best Practices: Iterating over Own Properties
    • Accessors (Getters and Setters)
      • Defining Accessors via an Object Literal
      • Defining Accessors via Property Descriptors
      • Accessors and Inheritance
    • Property Attributes and Property Descriptors
      • Property Attributes
        • Default values
      • Property Descriptors
      • Getting and Defining Properties via Descriptors
      • Copying an Object
      • Properties: Definition Versus Assignment
      • Inherited Read-Only Properties Cant Be Assigned To
      • Enumerability: Best Practices
    • Protecting Objects
      • Preventing Extensions
      • Sealing
      • Freezing
      • Pitfall: Protection Is Shallow
    • Layer 3: ConstructorsFactories for Instances
      • The new Operator Implemented in JavaScript
      • Terminology: The Two Prototypes
      • The constructor Property of Instances
        • Use cases for the constructor property
        • Best practice
      • The instanceof Operator
        • Pitfall: objects that are not instances of Object
        • Pitfall: crossing realms (frames or windows)
      • Tips for Implementing Constructors
        • Protection against forgetting new: strict mode
        • Returning arbitrary objects from a constructor
    • Data in Prototype Properties
      • Avoid Prototype Properties with Initial Values for Instance Properties
        • Best practice: dont share default values
        • Creating instance properties on demand
      • Avoid Nonpolymorphic Prototype Properties
      • Polymorphic Prototype Properties
    • Keeping Data Private
      • Private Data in the Environment of a Constructor (Crockford Privacy Pattern)
        • Public properties
        • Private values
        • Privileged methods
        • An example
        • The pros and cons of the Crockford privacy pattern
      • Private Data in Properties with Marked Keys
      • Private Data in Properties with Reified Keys
      • Keeping Global Data Private via IIFEs
        • Attaching private global data to a singleton object
        • Keeping global data private to all of a constructor
        • Attaching global data to a method
    • Layer 4: Inheritance Between Constructors
      • Inheriting Instance Properties
      • Inheriting Prototype Properties
      • Ensuring That instanceof Works
      • Overriding a Method
      • Making a Supercall
      • Avoiding Hardcoding the Name of the Superconstructor
      • Example: Constructor Inheritance in Use
      • Example: The Inheritance Hierarchy of Built-in Constructors
      • Antipattern: The Prototype Is an Instance of the Superconstructor
    • Methods of All Objects
      • Conversion to Primitive
      • Object.prototype.toLocaleString()
      • Prototypal Inheritance and Properties
    • Generic Methods: Borrowing Methods from Prototypes
      • Accessing Object.prototype and Array.prototype via Literals
      • Examples of Calling Methods Generically
      • Array-Like Objects and Generic Methods
        • Patterns for working with array-like objects
      • A List of All Generic Methods
    • Pitfalls: Using an Object as a Map
      • Pitfall 1: Inheritance Affects Reading Properties
        • Checking whether a property exists
        • Collecting property keys
        • Getting a property value
      • Pitfall 2: Overriding Affects Invoking Methods
      • Pitfall 3: The Special Property __proto__
      • The dict Pattern: Objects Without Prototypes Are Better Maps
        • Normal objects
        • Prototype-less objects
        • Recommendation
      • Best Practices
    • Cheat Sheet: Working with Objects
  • 18. Arrays
    • Overview
      • Arrays Are Maps, Not Tuples
      • Arrays Can Also Have Properties
    • Creating Arrays
      • The Array Constructor
        • Creating an empty array with a given length
        • Initializing an array with elements (avoid!)
      • Multidimensional Arrays
    • Array Indices
      • The in Operator and Indices
      • Deleting Array Elements
      • Array Indices in Detail
    • length
      • Manually Increasing the Length of an Array
      • Decreasing the Length of an Array
        • Clearing an array
        • Clearing shared arrays
      • The Maximum Length
    • Holes in Arrays
      • Creating Holes
      • Sparse Arrays Versus Dense Arrays
      • Which Operations Ignore Holes, and Which Consider Them?
        • Array iteration methods
        • Other array methods
        • The for-in loop
        • Function.prototype.apply()
      • Removing Holes from Arrays
    • Array Constructor Method
    • Array Prototype Methods
    • Adding and Removing Elements (Destructive)
    • Sorting and Reversing Elements (Destructive)
      • Comparing Numbers
      • Comparing Strings
      • Comparing Objects
    • Concatenating, Slicing, Joining (Nondestructive)
    • Searching for Values (Nondestructive)
    • Iteration (Nondestructive)
      • Examination Methods
      • Transformation Methods
      • Reduction Methods
    • Pitfall: Array-Like Objects
    • Best Practices: Iterating over Arrays
  • 19. Regular Expressions
    • Regular Expression Syntax
      • Atoms: General
      • Atoms: Character Classes
      • Atoms: Groups
      • Quantifiers
      • Assertions
      • Disjunction
    • Unicode and Regular Expressions
    • Creating a Regular Expression
      • Literal Versus Constructor
      • Flags
      • Instance Properties of Regular Expressions
      • Examples of Creating Regular Expressions
    • RegExp.prototype.test: Is There a Match?
    • String.prototype.search: At What Index Is There a Match?
    • RegExp.prototype.exec: Capture Groups
      • First Match (Flag /g Not Set)
      • All Matches (Flag /g Set)
    • String.prototype.match: Capture Groups or Return All Matching Substrings
    • String.prototype.replace: Search and Replace
      • Replacement Is a String
      • Replacement Is a Function
    • Problems with the Flag /g
    • Tips and Tricks
      • Quoting Text
      • Pitfall: Without an Assertion (e.g., ^, $), a Regular Expression Is Found Anywhere
      • Matching Everything or Nothing
        • Matching everything
        • Matching nothing
      • Manually Implementing Lookbehind
    • Regular Expression Cheat Sheet
  • 20. Dates
    • The Date Constructor
    • Date Constructor Methods
    • Date Prototype Methods
      • Time Unit Getters and Setters
      • Various Getters and Setters
      • Convert a Date to a String
    • Date Time Formats
      • Date Formats (No Time)
      • Time Formats (No Date)
      • Date Time Formats
    • Time Values: Dates as Milliseconds Since 1970-01-01
      • Converting a Date to a Number
  • 21. Math
    • Math Properties
    • Numerical Functions
    • Trigonometric Functions
    • Other Functions
  • 22. JSON
    • Background
      • Data Format
      • History
      • Grammar
    • JSON.stringify(value, replacer?, space?)
      • Data Ignored by JSON.stringify()
      • The toJSON() Method
    • JSON.parse(text, reviver?)
    • Transforming Data via Node Visitors
      • JSON.stringify()
      • JSON.parse()
  • 23. Standard Global Variables
    • Constructors
    • Error Constructors
    • Nonconstructor Functions
      • Encoding and Decoding Text
      • Categorizing and Parsing Numbers
    • Dynamically Evaluating JavaScript Code via eval() and new Function()
      • Evaluating Code Using eval()
        • Use eval() in strict mode
        • Indirect eval() evaluates in global scope
      • Evaluating Code Using new Function()
      • eval() Versus new Function()
      • Best Practices
        • Legitimate use cases
      • Conclusion
    • The Console API
      • How Standardized Is the Console API Across Engines?
      • Simple Logging
      • Checking and Counting
      • Formatted Logging
      • Profiling and Timing
    • Namespaces and Special Values
  • 24. Unicode and JavaScript
    • Unicode History
    • Important Unicode Concepts
    • Code Points
    • Unicode Encodings
    • JavaScript Source Code and Unicode
      • Source Code Internally
      • Source Code Externally
    • JavaScript Strings and Unicode
      • Escape Sequences
      • Refering to Astral Plane Characters via Escapes
      • Counting Characters
      • Unicode Normalization
    • JavaScript Regular Expressions and Unicode
      • Matching Any Code Unit and Any Code Point
      • Libraries
      • Recommended Reading and Chapter Sources
  • 25. New in ECMAScript 5
    • New Features
    • Syntactic Changes
    • New Functionality in the Standard Library
      • Metaprogramming
      • New Methods
      • JSON
    • Tips for Working with Legacy Browsers
• IV. Tips, Tools, and Libraries
  • 26. A Meta Code Style Guide
    • Existing Style Guides
    • General Tips
      • Code Should Be Consistent
      • Code Should Be Easy to Understand
    • Commonly Accepted Best Practices
      • Brace Styles
        • Allman style
        • 1TBS (One True Brace Style)
        • JavaScript
      • Prefer Literals to Constructors
      • Dont Be Clever
        • Conditional operator
        • Abbreviating if statements
        • Increment operator
        • Checking for undefined
        • Converting a number to an integer
      • Acceptable Cleverness
        • Default values
        • Generic methods
        • ECMAScript 5: trailing commas
        • ECMAScript 5: reserved words
    • Controversial Rules
      • Syntax
      • Variables
      • Object Orientation
      • Miscellaneous
    • Conclusion
  • 27. Language Mechanisms for Debugging
  • 28. Subclassing Built-ins
    • Terminology
    • Obstacle 1: Instances with Internal Properties
      • Workaround for Obstacle 1
      • Caveats
    • Obstacle 2: A Constructor That Cant Be Called as a Function
      • Workaround for Obstacle 2
    • Another Solution: Delegation
  • 29. JSDoc: Generating API Documentation
    • The Basics of JSDoc
      • Syntax
      • Naming Types
    • Basic Tags
    • Documenting Functions and Methods
    • Inline Type Information (Inline Doc Comments)
    • Documenting Variables, Parameters, and Instance Properties
    • Documenting Classes
      • Defining a Class via a Constructor Function
      • Defining a Class via an Object Literal
      • Defining a Class via an Object Literal with an @constructs Method
      • Subclassing
    • Other Useful Tags
  • 30. Libraries
    • Shims Versus Polyfills
    • Four Language Libraries
    • The ECMAScript Internationalization API
      • The ECMAScript Internationalization API, Edition 1
      • What Kind of Standard Is It?
      • When Can I Use It?
      • Further Reading
    • Directories for JavaScript Resources
  • 31. Module Systems and Package Managers
    • Module Systems
    • Package Managers
    • Quick and Dirty Modules
  • 32. More Tools
  • 33. What to Do Next
• Index
• About the Author
• Colophon
• Copyright

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