You Don't Know JS Yet: Get Started
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You Don't Know JS Yet: Get Started

Get to know JS

About the Book

The worldwide best selling You Don't Know JS book series is back for a 2nd edition: You Don't Know JS Yet. All 6 books are brand new, rewritten to cover all sides of JS for 2020 and beyond. You'll still get in-depth coverage of the core language, applied in useful code organization patterns for your programs. And of course, through Kyle's unique perspective and conversational tone, explore passionate, reasoned debate of the most common questions developers face.

Get Started, the first book in the new edition series, is where to start your journey of knowing JS more deeply. This book surveys the language in multiple layers of detail, laying out a roadmap with the other books as guides for your learning and growth. For any developer hoping to move from early JS experience to a deeper level, here is your first step to get started.

In Get Started, you'll explore:

  • How the JS language evolves, how JS programs actually work, and busting of common myths
  • The building blocks of JS: values, functions, and more
  • The roots and pillars of JS: types, closure, and prototypes


Frontend Masters is the premier sponsor of the 2nd edition of the *You Don't Know JS Yet* book series.

Frontend Masters helps you advance your skills with in-depth, modern front-end engineering courses, the highest quality video content available anywhere on the web. With over 150 courses to choose from, the expert content you need to take your development to the next level is here, so get started by joining today!

Among the amazing courses in the Frontend Masters library, Kyle's courses are the perfect companion materials to this book series. Check them all out, including these few specifically:

About the Author

Kyle Simpson
Kyle Simpson

Kyle Simpson likes to explore JS and FP techniques. He's written books, taught, and spoken publicly. He's currently helping build a culture of engineering excellence for his employer.

About the Contributors

Brian Holt
Brian Holt


Jasmine Kwityn
Jasmine Kwityn

Copy Editor

Simon St.Laurent
Simon St.Laurent

Content Editor

Table of Contents

  • Foreword
  • Preface
    • The Parts
    • The Title?
    • The Mission
    • The Path
  • Chapter 1: What Is JavaScript?
    • About This Book
    • What’s With That Name?
    • Language Specification
    • Many Faces
    • Backwards & Forwards
    • What’s in an Interpretation?
    • Strictly Speaking
    • Defined
  • Chapter 2: Surveying JS
    • Each File is a Program
    • Values
    • Declaring and Using Variables
    • Functions
    • Comparisons
    • How We Organize in JS
    • The Rabbit Hole Deepens
  • Chapter 3: Digging to the Roots of JS
    • Iteration
    • Closure
    • this Keyword
    • Prototypes
    • Asking “Why?”
  • Chapter 4: The Bigger Picture
    • Pillar 1: Scope and Closure
    • Pillar 2: Prototypes
    • Pillar 3: Types and Coercion
    • With the Grain
    • In Order
  • Appendix A: Exploring Further
    • Values vs. References
    • So Many Function Forms
    • Coercive Conditional Comparison
    • Prototypal “Classes”
  • Appendix B: Practice, Practice, Practice!
    • Practicing Comparisons
    • Practicing Closure
    • Practicing Prototypes
    • Suggested Solutions
  • Notes

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