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