Javascript DOES NOT in fact have built-in immutability similar to Clojure's immutable structures - those are shallow, runtime-enforced restrictions, while Clojure immutable structures provide deep, structural immutability. They are based on structural sharing and are very memory/performance efficient.
Default immutability in Clojure is pretty big deal idea. Rich Hickey spent around two years designing the language around them. They are not superficial runtime restrictions but are an essential part of the language's data model.
Default immutability in Clojure is pretty big deal idea. Rich Hickey spent around two years designing the language around them. They are not superficial runtime restrictions but are an essential part of the language's data model.