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The original first edition of the You Don’t Know JS book series is still available for those who want to reference it or prefer the original content.

First Edition Repository

Access the complete first edition on GitHub

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About the First Edition

The first edition of You Don’t Know JS was a groundbreaking series that helped countless developers gain a deeper understanding of JavaScript. Released over the course of several years, it covered the fundamental mechanisms of the JavaScript language in unprecedented detail.

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First Edition Books

The original series included six books:
  1. Up & Going - An introduction to programming and JavaScript basics
  2. Scope & Closures - Understanding JavaScript’s scope and closure mechanisms
  3. this & Object Prototypes - Deep dive into the this keyword and prototypal inheritance
  4. Types & Grammar - Exploring JavaScript’s built-in types and grammar
  5. Async & Performance - Asynchronous programming patterns and performance optimization
  6. ES6 & Beyond - New features in ES6 and future JavaScript additions
The first edition books are still freely available to read on GitHub, but they are no longer maintained or updated.

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Differences Between Editions

The second edition represents a significant evolution of the series, with major changes in structure, content, and scope.

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What Changed

The second edition is completely rewritten to reflect modern JavaScript (ES6+) as the baseline, rather than treating newer features as “future additions.” The content assumes readers are working with contemporary JavaScript environments.
The second edition reorganizes topics for better learning flow:
  • Get Started - A more comprehensive introduction
  • Scope & Closures - Completely rewritten and expanded
  • Objects & Classes - Combines and updates prototypes and object content
  • Types & Grammar - Refined and modernized
  • Some topics were consolidated or reimagined for clarity
Some planned books were cancelled in the second edition:
  • Sync & Async - Cancelled as a standalone book
  • ES.Next & Beyond - Cancelled as modern features are integrated throughout
These topics are covered within other books or omitted in favor of more relevant content.
The second edition uses a different publishing approach:
  • Self-published through GetiPub
  • “The Unbooks” collection bundles later books together
  • Available on Leanpub and Amazon
  • Still freely readable on GitHub

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Which Edition Should You Read?

Read Second Edition If...

  • You want the most current content
  • You’re learning modern JavaScript (ES6+)
  • You prefer updated examples and explanations
  • You want the author’s refined teaching approach

Reference First Edition If...

  • You’re maintaining legacy JavaScript code
  • You want to see how topics were originally explained
  • You’re comparing the evolution of concepts
  • You need coverage of pre-ES6 patterns
For most readers, the second edition is recommended. It represents the author’s latest thinking and is written for the JavaScript you’ll use today.

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No Translations for First Edition

Foreign language translations are only accepted for the second edition books. New translations of first edition content will not be accepted.
If you’re interested in translating You Don’t Know JS Yet, please see the Contributing guide for information on translating the second edition.

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Legacy and Impact

The first edition of You Don’t Know JS had an enormous impact on the JavaScript community:
  • Over 150,000 stars on GitHub (across both editions)
  • Translated into dozens of languages
  • Used in bootcamps and self-study programs worldwide
  • Helped establish a culture of “deep learning” in JavaScript education
The second edition builds on this foundation while moving the content forward for the next generation of JavaScript developers.
The first edition books are complete and no longer being updated. All future development focuses on the second edition.

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Access the First Edition

Ready to explore the original series?

Visit First Edition on GitHub

Read all six books of the first edition for free on GitHub

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