--- product_id: 13164702 title: "You Don't Know JS: Async & Performance" price: "€ 54.77" currency: EUR in_stock: true reviews_count: 13 url: https://www.desertcart.be/products/13164702-you-dont-know-js-async-and-performance store_origin: BE region: Belgium --- # You Don't Know JS: Async & Performance **Price:** € 54.77 **Availability:** ✅ In Stock ## Quick Answers - **What is this?** You Don't Know JS: Async & Performance - **How much does it cost?** € 54.77 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.be](https://www.desertcart.be/products/13164702-you-dont-know-js-async-and-performance) ## Best For - Customers looking for quality international products ## Why This Product - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Description You Don't Know JS: Async & Performance [Simpson, Kyle] on desertcart.com. *FREE* shipping on qualifying offers. You Don't Know JS: Async & Performance Review: Tremendous, but challenging. - This penultimate edition of the You Don't Know JS series explores everything async: Promises and Generators, mainly. As usual, the content was deep and the examples challenging (in this edition especially so). This book is certainly not for the feint of heart; if you're not an advanced developer and you don't know about these topics, you might consider reading some simpler introductory material online before tackling this. The one negative was the editing; there were many places where a sharp editor could have really clarified and simplified matters. There were a number of places where I'd read a section two or three times, and basically say to myself, "so Kyle's saying X Y Z," and then three paragraphs later see him say almost verbatim, "X Y Z." On the one hand it's always nice seeing that you correctly interpreted something difficult, but on the other a more straightforward presentation would have helped. And many other areas would have similarly benefited from a tightening up of the language, and stating more clearly and up front what the lessons to follow were. But to be clear, the above criticism should not for a moment prevent a senior JS developer from tackling this book. It'll be well worth your time, and you'll no doubt learn a tremendous amount. Review: Solid, Well-Focused Deep Dive - This book offers a solid deep dive into various asynchronous and performance issues in javascript - especially when js is deploy in a node.js runtime able to launch operations vastly more complex than javascript executed in a Web browser. The author occassionaly delves into his own subjunctive proposals for the future of JavaScript. Those passages are no doubt well informed and mayne useful to the JS development community. For a reader trying to better understand JS as it is now, those passages might compete for attention and memory best budgeted to understanding tools in the drawer at this time. Overall, side tracks exploring potential devlopment paths not yet included in JacaScript does not at all diminish the authors skilled explanation of how JavaScript works. Particularly intersting to me was an acknowledgement that tried and true methods.... callbacks in particular.. remain part of many workflows until developers make deliberate efforts to learn and practice new approaches such as promises. The book's compare-and-contrast approach to callbacks, promises and generators can help a devloper decide when to push through doing ot the same old way and when to deploy new tools. ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | 1491904224 | | Best Sellers Rank | #871,043 in Books ( See Top 100 in Books ) #149 in JavaScript Programming (Books) #792 in Computer Programming Languages #2,143 in Programming Languages (Books) | | Book 4 of 6 | You Don't Know Js | | Customer Reviews | 4.5 4.5 out of 5 stars (177) | | Dimensions | 6 x 0.67 x 9 inches | | Edition | 1st | | ISBN-10 | 9781491904220 | | ISBN-13 | 978-1491904220 | | Item Weight | 14.4 ounces | | Language | English | | Print length | 293 pages | | Publication date | April 7, 2015 | | Publisher | O'Reilly Media | ## Images ![You Don't Know JS: Async & Performance - Image 1](https://m.media-amazon.com/images/I/91wXqGQsUFL.jpg) ## Customer Reviews ### ⭐⭐⭐⭐⭐ Tremendous, but challenging. *by A***S on April 11, 2015* This penultimate edition of the You Don't Know JS series explores everything async: Promises and Generators, mainly. As usual, the content was deep and the examples challenging (in this edition especially so). This book is certainly not for the feint of heart; if you're not an advanced developer and you don't know about these topics, you might consider reading some simpler introductory material online before tackling this. The one negative was the editing; there were many places where a sharp editor could have really clarified and simplified matters. There were a number of places where I'd read a section two or three times, and basically say to myself, "so Kyle's saying X Y Z," and then three paragraphs later see him say almost verbatim, "X Y Z." On the one hand it's always nice seeing that you correctly interpreted something difficult, but on the other a more straightforward presentation would have helped. And many other areas would have similarly benefited from a tightening up of the language, and stating more clearly and up front what the lessons to follow were. But to be clear, the above criticism should not for a moment prevent a senior JS developer from tackling this book. It'll be well worth your time, and you'll no doubt learn a tremendous amount. ### ⭐⭐⭐⭐⭐ Solid, Well-Focused Deep Dive *by B***R on August 27, 2017* This book offers a solid deep dive into various asynchronous and performance issues in javascript - especially when js is deploy in a node.js runtime able to launch operations vastly more complex than javascript executed in a Web browser. The author occassionaly delves into his own subjunctive proposals for the future of JavaScript. Those passages are no doubt well informed and mayne useful to the JS development community. For a reader trying to better understand JS as it is now, those passages might compete for attention and memory best budgeted to understanding tools in the drawer at this time. Overall, side tracks exploring potential devlopment paths not yet included in JacaScript does not at all diminish the authors skilled explanation of how JavaScript works. Particularly intersting to me was an acknowledgement that tried and true methods.... callbacks in particular.. remain part of many workflows until developers make deliberate efforts to learn and practice new approaches such as promises. The book's compare-and-contrast approach to callbacks, promises and generators can help a devloper decide when to push through doing ot the same old way and when to deploy new tools. ### ⭐⭐⭐⭐ Great but flawed in certain ways *by I***T on May 28, 2020* Well I'm a big fan of Kyle, I have all 5 of these books, and also his book on functional js. But this is quite a tricky topic, and he does not tackle it perfectly. He does a good job, but there are some noteworthy flaws. First of all, on multiple occasions when talking about async events and so on he gets lost in quite long (10 page), and purely abstract story-telling type of explanations that simply did not seem necessary, well grounded, or that helpful to anyone beyond a sophore college student. That's a minor gripe, but it is worth noting. Secondly, and more importantly, his explanation on promises... it's 70 pages on promises, it's sophisticated, it goes into great depth, but it never once clearly states... what the basic promise syntax is. Particularly, how to create a new promise is never mentioned - i.e. what the point of the promise constructor is (p = new Promise(...) ) and how to use it. Bear in mind this was after 6-7 pages of abstract groundwork-laying and storytelling aimed at complete beginners. I had to look at his ES6 book / online resources to get the basic syntax. The whole time I was wondering... ok but what is a promise? And he keeps telling you you'll find out, but you never quite do. His code examples were also fairly confusing. It's a difficult topic but it was made more difficult from the ambiguity introduced by relying on various pre-built functions in place of constructing the promises, making the raw async callbacks, etc. This wasn't just a problem in the promises chapter, it was also a problem in callbacks and generators to some degree. After figuring out how promises work mechanically, and the role of the constructor & various callbacks, then rereading the book... it's a great book. Worth buying, full of depth and complexity, worth multiple reads to gradually master all that's packed into the book. But given the flaws mentioned, and a few others, I can't honestly give it 5 stars despite how much I love Kyles books. But I don't want to knock it too badly, because for advanced readers that know promises and other async techniques already, this is probably not a downside. It is however a design flaw considering the long winded beginner explanations. I'd give it 4.5 stars if I had the option. --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.be/products/13164702-you-dont-know-js-async-and-performance](https://www.desertcart.be/products/13164702-you-dont-know-js-async-and-performance) --- *Product available on Desertcart Belgium* *Store origin: BE* *Last updated: 2026-05-21*