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YDKJS

Free

A deep dive into the core mechanisms of JavaScript

FreeFree tier
Type
Open Source

About YDKJS

You Don't Know JS Yet (YDKJS) is a comprehensive, multi-volume book series by Kyle Simpson that dives deep into the core mechanisms of the JavaScript language. The second edition covers topics such as scope, closures, objects, classes, types, grammar, async, and more. All content is available to read online for free under a Creative Commons license, with physical and ebook copies available for purchase. The series is widely regarded as essential reading for developers seeking a thorough understanding of JavaScript.

Key Features

Comprehensive series of books on JavaScript mechanics
Second edition with updated and expanded content
Available to read online for free
Covers scope, closures, objects, classes, types, grammar, and async
Written by renowned JavaScript educator Kyle Simpson
Creative Commons licensed for non-commercial use

Pros & Cons

Pros
  • Free online access to all content
  • In-depth, expert-level coverage of JavaScript internals
  • Well-respected and widely recommended in the developer community
  • Clear explanations with practical examples
  • Available in multiple formats (online, ebook, print)
Cons
  • Some planned books (Sync & Async, ES.Next & Beyond) were canceled for the second edition
  • Objects & Classes and Types & Grammar are still in draft form
  • Assumes some prior JavaScript knowledge; not a beginner tutorial for absolute newcomers

Best For

Learning JavaScript fundamentals in depthReference for advanced JavaScript conceptsSelf-study for developers transitioning from beginner to expertTeaching material for JavaScript workshops and courses

FAQ

Is You Don't Know JS free?
Yes, all books are available to read online for free on GitHub, licensed under Creative Commons Attribution-NonCommercial-NoDerivs 4.0.
Is this the second edition?
Yes, the repository contains the second edition (You Don't Know JS Yet). The first edition books are also available in a separate location.
What is the recommended reading order?
The author recommends starting with 'Get Started', followed by 'Scope & Closures', then the other books in order as they become available.
Can I purchase physical copies?
Yes, published books are sold through Leanpub and Amazon, as well as other book retail sources.