When I want to ensure strict immutability, I use an implementation of deepFreeze (https://github.com/jsdf/deep-freeze https://github.com/jsdf/deep-freeze) that

When I want to ensure strict immutability, I use an implementation of deepFreeze (https://github.com/jsdf/deep-freeze https://github.com/jsdf/deep-freeze) that recursively calls Object.freeze() on all child properties. Obviously slower than strict browser support. Does ClojureScript rely on the Clojure compiler to ensure the properties aren't modified or is there some polyfill?