Understanding ECMAScript 6 the definitive guide for JavaScript developers = the definitive guide for JavaScript developers

ECMAScript 6 represents the biggest update to the core of JavaScript in the history of the language. In Understanding ECMAScript 6, expert developer Nicholas C. Zakas provides a complete guide to the object types, syntax, and other exciting changes that ECMAScript 6 brings to JavaScript. Every chapter is packed with example code that works in any JavaScript environment so you’ll be able to see new features in action. You’ll learn:• How ECMAScript 6 class syntax relates to more familiar JavaScript concepts• What makes iterators and generators useful• How arrow functions differ from regular functions• Ways to store data with sets, maps, and more• The power of inheritance• How to improve asynchronous programming with promises• How modules change the way you organize codeWhether you’re a web developer or a Node.js developer, you’ll find Understanding ECMAScript 6 indispensable on your journey from ECMAScript 5 to ECMAScript 6.Author Bio Nicholas C. Zakas has been working on web applications since 2000, focusing on frontend development, and is known for writing and speaking about frontend best practices. He honed his experience during his five years at Yahoo!, where he was principal frontend engineer for the Yahoo! home page. He is the author of several books, including The Principles of Object-Oriented JavaScript (No Starch Press) and Professional JavaScript for Web Developers (Wrox). Foreword Acknowledgments Introduction The Road to ECMAScript 6 About This Book Browser and Node.js Compatibility Who This Book Is For Overview Conventions Used Help and Support Chapter 1: Block Bindings var Declarations and Hoisting Block-Level Declarations let Declarations No Redeclaration const Declarations The Temporal Dead Zone Block Bindings in Loops Functions in Loops let Declarations in Loops const Declarations in Loops Global Block Bindings Emerging Best Practices for Block Bindings Summary Chapter 2: Strings and Regular Expressions Better Unicode Support UTF-16 Code Points The codePointAt() Method The String.fromCodePoint() Method The normalize() Method The Regular Expression u Flag Other String Changes Methods for Identifying Substrings The repeat() Method Other Regular Expression Changes The Regular Expression y Flag Duplicating Regular Expressions The flags Property Template Literals Basic Syntax Multiline Strings Making Substitutions Tagged Templates Summary Chapter 3: Functions Functions with Default Parameter Values Simulating Default Parameter Values in ECMAScript 5 Default Parameter Values in ECMAScript 6 How Default Parameter Values Affect the arguments Object Default Parameter Expressions Default Parameter TDZ Working with Unnamed Parameters Unnamed Parameters in ECMAScript 5 Rest Parameters Increased Capabilities of the Function Constructor The Spread Operator The name Property Choosing Appropriate Names Special Cases of the name Property Clarifying the Dual Purpose of Functions Determining How a Function Was Called in ECMAScript 5 The new.target Metaproperty Block-Level Functions Deciding When to Use Block-Level Functions Block-Level Functions in Non-Strict Mode Arrow Functions Arrow Function Syntax Creating Immediately Invoked Function Expressions No this Binding Arrow Functions and Arrays No arguments Binding Identifying Arrow Functions Tail Call Optimization How Tail Calls Are Different in ECMAScript 6 How to Harness Tail Call Optimization Summary Chapter 4: Expanded Object Functionality Object Categories Object Literal Syntax Extensions Property Initializer Shorthand Concise Methods Computed Property Names New Methods The Object.is() Method The Object.assign() Method Duplicate Object Literal Properties Own Property Enumeration Order Enhancements for Prototypes Changing an Object’s Prototype Easy Prototype Access with Super References A Formal Method Definition Summary Chapter 5: Destructuring for Easier Data Access Why Is Destructuring Useful? Object Destructuring Destructuring Assignment Default Values Assigning to Different Local Variable Names Nested Object Destructuring Array Destructuring Destructuring Assignment Default Values Nested Destructuring Rest Items Mixed Destructuring Destructured Parameters Destructured Parameters Are Required Default Values for Destructured Parameters Summary Chapter 6: Symbols and Symbol Properties Creating Symbols Using Symbols Sharing Symbols Symbol Coercion Retrieving Symbol Properties Exposing Internal Operations with Well-Known Symbols The Symbol.hasInstance Method The Symbol.isConcatSpreadable Property The Symbol.match, Symbol.replace, Symbol.search, and Symbol.split Properties The Symbol.toPrimitive Method The Symbol.toStringTag Property The Symbol.unscopables Property Summary Chapter 7: Sets and Maps Sets and Maps in ECMAScript 5 Problems with Workarounds Sets in ECMAScript 6 Creating Sets and Adding Items Removing Items The forEach() Method for Sets Converting a Set to an Array Weak Sets Maps in ECMAScript 6 Map Methods Map Initialization The forEach() Method for Maps Weak Maps Summary Chapter 8: Iterators and Generators The Loop Problem What Are Iterators? What Are Generators? Generator Function Expressions Generator Object Methods Iterables and for-of Loops Accessing the Default Iterator Creating Iterables Built-In Iterators Collection Iterators String Iterators NodeList Iterators The Spread Operator and Nonarray Iterables Advanced Iterator Functionality Passing Arguments to Iterators Throwing Errors in Iterators Generator Return Statements Delegating Generators Asynchronous Task Running A Simple Task Runner Task Running with Data An Asynchronous Task Runner Summary Chapter 9: Introducing JavaScript Classes Class-Like Structures in ECMAScript 5 Class Declarations A Basic Class Declaration Why Use the Class Syntax? Class Expressions A Basic Class Expression Named Class Expressions Classes as First-Class Citizens Accessor Properties Computed Member Names Generator Methods Static Members Inheritance with Derived Classes Shadowing Class Methods Inherited Static Members Derived Classes from Expressions Inheriting from Built-Ins The Symbol.species Property Using new.target in Class Constructors Summary Chapter 10: Improved Array Capabilities Creating Arrays The Array.of() Method The Array.from() Method New Methods on All Arrays The find() and findIndex() Methods The fill() Method The copyWithin() Method Typed Arrays Numeric Data Types Array Buffers Manipulating Array Buffers with Views Similarities Between Typed and Regular Arrays Common Methods The Same Iterators The of() and from() Methods Differences Between Typed and Regular Arrays Behavioral Differences Missing Methods Additional Methods Summary Chapter 11: Promises and Asynchronous Programming Asynchronous Programming Background The Event Model The Callback Pattern Promise Basics The Promise Life Cycle Creating Unsettled Promises Creating Settled Promises Executor Errors Global Promise Rejection Handling Node.js Rejection Handling Browser Rejection Handling Chaining Promises Catching Errors Returning Values in Promise Chains Returning Promises in Promise Chains Responding to Multiple Promises The Promise.all() Method The Promise.race() Method Inheriting from Promises Asynchronous Task Running Summary Chapter 12: Proxies and the Reflection API The Array Problem Introducing Proxies and Reflection Creating a Simple Proxy Validating Properties Using the set Trap Object Shape Validation Using the get Trap Hiding Property Existence Using the has Trap Preventing Property Deletion with the deleteProperty Trap Prototype Proxy Traps How Prototype Proxy Traps Work Why Two Sets of Methods? Object Extensibility Traps Two Basic Examples Duplicate Extensibility Methods Property Descriptor Traps Blocking Object.defineProperty() Descriptor Object Restrictions Duplicate Descriptor Methods The ownKeys Trap Function Proxies with the apply and construct Traps Validating Function Parameters Calling Constructors Without new Overriding Abstract Base Class Constructors Callable Class Constructors Revocable Proxies Solving the Array Problem Detecting Array Indexes Increasing length when Adding New Elements Deleting Elements When Reducing length Implementing the MyArray Class Using a Proxy as a Prototype Using the get Trap on a Prototype Using the set Trap on a Prototype Using the has Trap on a Prototype Proxies as Prototypes on Classes Summary Chapter 13: Encapsulating Code with Modules What Are Modules? Basic Exporting Basic Importing Importing a Single Binding Importing Multiple Bindings Importing an Entire Module A Subtle Quirk of Imported Bindings Renaming Exports and Imports Default Values in Modules Exporting Default Values Importing Default Values Re-exporting a Binding Importing Without Bindings Loading Modules Using Modules in Web Browsers Browser Module Specifier Resolution Summary Appendix A: Minor Changes in ECMAScript 6 Working with Integers Identifying Integers Safe Integers New Math Methods Unicode Identifiers Formalizing the __proto__ Property Appendix B: Understanding ECMAScript 7 (2016) The Exponentiation Operator Order of Operations Operand Restriction The Array.prototype.includes() Method How to Use Array.prototype.includes() Value Comparison A Change to Function-Scoped Strict Mode Index ECMAScript 6 represents the biggest update to the core of JavaScript in the history of the language. __In Understanding ECMAScript 6__, expert developer Nicholas C. Zakas provides a complete guide to the object types, syntax, and other exciting changes that ECMAScript 6 brings to JavaScript. Every chapter is packed with example code that works in any JavaScript environment so you'll be able to see new features in action. You'll learn: * How ECMAScript 6 class syntax relates to more familiar JavaScript concepts * What makes iterators and generators useful * How arrow functions differ from regular functions * Ways to store data with sets, maps, and more * The power of inheritance * How to improve asynchronous programming with promises * How modules change the way you organize code Whether you're a web developer or a Node.js developer, you'll find __Understanding ECMAScript 6__ indispensable on your journey from ECMAScript 5 to ECMAScript 6.