An étude, according to Wikipedia, is “an instrumental musical composition, usually short and of considerable difficulty, usually designed to provide practice material for perfecting a particular musical skill.”
In this book, you will find descriptions of programs that you can compose (write) in ClojureScript. The programs will usually be short, and each one has been designed to provide practice material for a particular ClojureScript programming area. Unlike musical études, these programs have not been designed to be of considerable difficulty, though they may ask you to stretch a bit beyond the immediate material and examples that you find in most ClojureScript books or online references.
These études are not intended to introduce you to individual ClojureScript concepts. That ground is covered quite nicely by ClojureScript Koans, 4Clojure, and ClojureScript Unraveled. Instead, these études take the form of small projects that do something that is (somewhat) useful. They are much along the lines of the programming katas given in chapter 10 of Living Clojure by Carin Meier. If Koans, 4Clojure, and ClojureScript Unraveled ask you to write programs at the level of chemical elements, in this book you are constructing simple molecules.
This book is open source, so if you’d like to contribute, make a correction, or otherwise participate in the project, check out jdeisenberg/etudes-for-clojurescript on GitHub for details. If we accept your work, we’ll add you to the contributors chapter.
Thanks to Simon St. Laurent and Meghan Blanchette at O’Reilly Media, who encouraged me to write this book. Thanks also to all the people
on the #clojurescript IRC channel, who patiently answered my questions.