No matter how much experience you have with JavaScript, you don't fully understand the language. 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, renderers, and Web Workers that allow you to create advanced single-page web applications and escape callback hell in the process.Like the other books in this series, You Don't Know JS: Async & Performance dives into the more difficult parts of the language that many JavaScript programmers avoid. Armed with this knowledge, you can become a true JavaScript master.With this book you will:Explore JavaScript old and new ways to handle asynchronous programmingUnderstand how callbacks allow third parties to control the execution of your programAddress the "inversion of control" issue with JavaScript PromisesUse constructors to express asynchronous flow in a sequential, synchronized-looking wayTackle program-level performance with Web Workers, SIMD, and asm.jsLearn valuable resources and techniques for benchmarking and adjusting your expressions and expressions