What This Book Is
This is a book about JavaScript. It is also a book about Lykn. These are not two subjects wearing the same dust jacket — they are, like the language itself, a symbiosis.
Sources
Every chapter in this book maps to a set of concepts drawn from four major JavaScript references: Exploring JavaScript, Deep JavaScript, Eloquent JavaScript, and JavaScript: The Definitive Guide. Over 1,500 concepts have been catalogued, categorized, and distributed across the chapters that follow. When you learn about bind in Lykn, you are learning about const and let in JavaScript — their scoping rules, their hoisting behaviour (or deliberate lack thereof), their relationship to the temporal dead zone. When you learn about func, you are learning about JavaScript functions, parameter handling, closures, and the this binding problem that func quietly eliminates by not having this at all.
The surface language is how you will write. JavaScript is what you will understand.
The Voice
A note about the voice. You will have noticed that this book does not read like a typical technical manual. The chapter you are reading opened with an adaptation of Monty Python’s Dead Parrot Sketch, and subsequent chapters will open with similarly adapted sketches: the Spanish Inquisition, the Ministry of Silly Walks, the Cheese Shop, the Lumberjack Song, and others. This is not decoration. Each sketch dramatizes the chapter’s core tension — the conceptual problem that the technical content resolves.
Every joke in this book, if you look closely, contains a technical insight. Every technical insight, if you look closely, is structured like a joke. A reader who skips every humorous passage will still learn everything they need. A reader who reads only the humorous passages will, surprisingly, learn quite a lot. But the intended experience is both at once, because programming is difficult enough without also being dull, and parentheses are long enough without the prose around them being dry.
A Fruitng Body
There is one more thing to know before you begin. Lykn is a young language. Its surface compiler is in active development. The features described in this book are the features that exist and work, not aspirational features on a roadmap. It has, in fact, already been used in production. However, where a feature is planned but not yet implemented, this book says so. Where a design decision is settled but the code is still being written, this book says that too. Honesty about the state of things is a form of respect for the reader, and this book aims to be respectful — even when it is, simultaneously, being somewhat ridiculous.