From the homepage:
ClojureScript is a dialect of Clojure that targets JavaScript as a deployment platform.
From the rationale:
ClojureScript seeks to address the weak link in the client/embedded application development story by replacing JavaScript with Clojure, a robust, concise and powerful programming language. In its implementation, ClojureScript adopts the strategy of the Google Closure library and compiler, and is able to effectively leverage both tools, gaining a large, production-quality library and whole-program optimization. ClojureScript brings the rich data structure set, functional programming, macros, reader, destructuring, polymorphism constructs, state discipline and many other features of Clojure to every place JavaScript reaches.
Just in case you ever work on the client side of topic maps. 🙂