The map works similarly to several of the other methods we've seen so far. It takes a function that receives an array element as a parameter and returns some value. Those values are collected into a new array, and that new array is returned by the map method.
- Title Page
- Copyright and Credits
- Dedication
- PacktPub.com
- Contributors
- Preface
- Building with Modules
- Introduction
- Installing and configuring - Chrome
- Installing and configuring - Firefox
- Installing Python, using SimpleHTTPServer to host a local static file server
- Creating an HTML page that loads an ECMAScript module
- Exporting/importing multiple modules for external use
- Renaming imported modules
- Nesting modules under a single namespace
- Staying Compatible with Legacy Browsers
- Introduction
- Installing Node.js with NVM – Linux and macOS
- Installing Node.js with NVM: Windows
- Installing and configuring webpack
- Adding fallback script tags to load client bundles
- Shimming methods with Babel Polyfill
- Supporting new language features with Babel
- Using tools to analyze webpack bundles
- Working with Promises
- Working with async/await and Functions
- Introduction
- Creating promises with an async function
- Awaiting the result of async functions
- Using async results in a Promise chain
- Awaiting multiple results in a series
- Awaiting multiple results concurrently
- Using Promise.all to collect an array of async results
- Handling errors when awaiting an async function
- Handling errors thrown inside of Promise.all
- Using finally to ensure an operation is performed
- Web Workers, Shared Memory, and Atomics
- Introduction
- Enabling SharedArrayBuffers in Firefox
- Enabling SharedArrayBuffers in Chrome
- Performing work on separate threads with Web Workers
- Sending messages to and from Web Workers
- Sending data to a Web Worker
- Stopping workers with terminate
- Creating SharedArrayBuffer
- Sending SharedArrayBuffer to a Web Worker
- Reading SharedArray from multiple Web Workers
- Using Atomics to coordinate the use of shared memory
- Using promises to provide a simple interface for a worker
- Plain Objects
- Introduction
- Using Object.assign to add properties to an object
- Using Object.entries to get iterable property-name pairs
- Using Object.is to compare two values
- Defining function properties as methods on a plain object
- Defining read-only props with Object.defineProperty
- Overriding read-only props with Object.defineProperty
- Creating a non-enumerable property with Object.defineProperty
- Creating an object using object structuring
- Picking values from an object using destructuring
- Using a spread operator to combine objects
- Creating Classes
- Inheritance and Composition
- Introduction
- Extending a class
- Assigning additional properties with constructor arguments
- Overriding parent class instance methods
- Overriding parent class static methods
- Calling super methods
- Using composition rather than inheritance to add behavior
- Using mix-ins to add behavior
- Passing a class as an argument
- Checking class inheritance with Object.getPrototypeOf
- Using throw to simulate abstract classes
- Larger Structures with Design Patterns
- Introduction
- Defining steps with template functions
- Assembling customized instances with builders
- Replicating instances with factories
- Processing a structure with the visitor pattern
- Using a singleton to manage instances
- Modifying an existing design pattern to fit different use cases
- Combining existing design patterns to fit different use cases
- Working with Arrays
- Introduction
- Using Array#find and Array#filter to find values in an array
- Using Array#slice to get a subset of the array
- Using Array#every and Array#some to test array values
- Using Array.map to produce values
- Using Array.reduce to transform data
- Extracting array members with destructuring
- Getting the head and tail of array using the rest operator
- Combining arrays with the spread operator
- Working with Maps and Symbols
- Introduction
- Using Symbol to create a local instance
- Using Symbol.for to create a global instance
- Using Symbol to simulate enums
- Setting and deleting entries from Map
- Creating a Map from the existing data
- Creating a class that wraps Map to work with specific complex types
- Setting and deleting entries from WeakMap
- Creating a WeakMap from existing data  
- Creating a class that uses WeakMap to work with specific complex types
- Working with Sets
- Introduction
- Adding and deleting items from a Set
- Creating a Set from existing data
- Adding and deleting items from WeakSet
- Creating a WeakSet from existing data
- Finding the union of two sets
- Finding the intersection of two sets
- Finding the difference between two sets
- Creating a class that wraps a Set to work with more complex types
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