No matter how much experience you have with JavaScript, odds are you don’t fully understand the language. This concise yet in-depth guide takes you inside scope and closures, two core concepts you need to know to become a more efficient and effective JavaScript programmer. You’ll learn how and why they work, and how an understanding of closures can be a powerful part of your development skillset. Like other books in the "You Don’t Know JS" series, Scope and Closures dives into trickier parts of the language that many JavaScript programmers simply avoid. Armed with this knowledge, you can achieve true JavaScript mastery. Learn about scope, a set of rules to help JavaScript engines locate variables in your code Go deeper into nested scope, a series of containers for variables and functions Explore function- and block-based scope, “hoisting”, and the patterns and benefits of scope-based hiding Discover how to use closures for synchronous and asynchronous tasks, including the creation of JavaScript libraries

It’s easy to learn parts of JavaScript, but much harder to learn it completely—or even sufficiently—whether you’re new to the language or have used it for years. With the "You Don’t Know JS" book series, you’ll get a more complete understanding of JavaScript, including trickier parts of the language that many experienced JavaScript programmers simply avoid. The series’ first book, Up & Going, provides the necessary background for those of you with limited programming experience. By learning the basic building blocks of programming, as well as JavaScript’s core mechanisms, you’ll be prepared to dive into the other, more in-depth books in the series—and be well on your way toward true JavaScript. With this book you will: Learn the essential programming building blocks, including operators, types, variables, conditionals, loops, and functions Become familiar with JavaScript's core mechanisms such as values, function closures, this, and prototypes Get an overview of other books in the series—and learn why it’s important to understand all parts of JavaScript

It seems like there's never been as much widespread desire before to learn JS. But with a million blogs, books, and videos out there, just where do you start?The worldwide best selling "You Don't Know JS" book series is back for a 2nd edition: "You Don't Know JS Yet". All 6 books are brand new, rewritten to cover all sides of JS for 2020 and beyond."Get Started" prepares you for the journey ahead, first surveying the language then detailing how the rest of the You Don't Know JS Yet book series guides you to knowing JS more deeply.

No matter how much experience you have with JavaScript, odds are you don’t fully understand the language. As part of the "You Don’t Know JS" series, this compact guide focuses on new features available in ECMAScript 6 (ES6), the latest version of the standard upon which JavaScript is built. Like other books in this series, You Don’t Know JS: ES6 & Beyond dives into trickier parts of the language that many JavaScript programmers either avoid or know nothing about. Armed with this knowledge, you can achieve true JavaScript mastery. With this book, you will: Learn new ES6 syntax that eases the pain points of common programming idioms Organize code with iterators, generators, modules, and classes Express async flow control with Promises combined with generators Use collections to work more efficiently with data in structured ways Leverage new API helpers, including Array, Object, Math, Number, and String Extend your program’s capabilities through meta programming Preview features likely coming to JS beyond ES6

No matter how much experience you have with JavaScript, odds are you don’t fully understand the language. As part of the "You Don’t Know JS" series, this concise yet in-depth guide focuses on new asynchronous features and performance techniques—including Promises, generators, and Web Workers—that let you create sophisticated single-page web applications and escape callback hell in the process. Like other books in this series, You Don’t Know JS: Async & Performance dives into trickier parts of the language that many JavaScript programmers simply avoid. Armed with this knowledge, you can become a true JavaScript master. With this book you will: Explore old and new JavaScript methods for handling asynchronous programming Understand how callbacks let third parties control your program’s execution Address the "inversion of control" issue with JavaScript Promises Use generators to express async flow in a sequential, synchronous-looking fashion Tackle program-level performance with Web Workers, SIMD, and asm.js Learn valuable resources and techniques for benchmarking and tuning your expressions and statements

No matter how much experience you have with JavaScript, odds are you don’t fully understand the language. This concise, in-depth guide takes you inside JavaScript’s this structure and object prototypes. You’ll learn how they work and why they’re integral to behavior delegation—a design pattern in which objects are linked, rather than cloned. Like other books in the “You Don’t Know JS” series, this and Object Prototypes dives into trickier parts of the language that many JavaScript programmers simply avoid. Armed with this knowledge, you can become a true JavaScript master. With this book you will: Explore how the this binding points to objects based on how the function is called Look into the nature of JS objects and why you’d need to point to them Learn how developers use the mixin pattern to fake classes in JS Examine how JS’s prototype mechanism forms links between objects Learn how to move from class/inheritance design to behavior delegation Understand how the OLOO (objects-linked-to-other-objects) coding style naturally implements behavior delegation

Most programming languages contain good and bad parts, but JavaScript has more than its share of the bad, having been developed and released in a hurry before it could be refined. This authoritative book scrapes away these bad features to reveal a subset of JavaScript that's more reliable, readable, and maintainable than the language as a whole—a subset you can use to create truly extensible and efficient code. Considered the JavaScript expert by many people in the development community, author Douglas Crockford identifies the abundance of good ideas that make JavaScript an outstanding object-oriented programming language-ideas such as functions, loose typing, dynamic objects, and an expressive object literal notation. Unfortunately, these good ideas are mixed in with bad and downright awful ideas, like a programming model based on global variables. When Java applets failed, JavaScript became the language of the Web by default, making its popularity almost completely independent of its qualities as a programming language. In JavaScript: The Good Parts, Crockford finally digs through the steaming pile of good intentions and blunders to give you a detailed look at all the genuinely elegant parts of JavaScript, including: Syntax Objects Functions Inheritance Arrays Regular expressions Methods Style Beautiful features The real beauty? As you move ahead with the subset of JavaScript that this book presents, you'll also sidestep the need to unlearn all the bad parts. Of course, if you want to find out more about the bad parts and how to use them badly, simply consult any other JavaScript book. With JavaScript: The Good Parts, you'll discover a beautiful, elegant, lightweight and highly expressive language that lets you create effective code, whether you're managing object libraries or just trying to get Ajax to run fast. If you develop sites or applications for the Web, this book is an absolute must.