&gt; In the expressjs example, I wonder how practical is to do all that interop instead of just using plain JS?<p>It depends. Interop in clojurescript isn&#x27;t any more difficult than using plain JS but if your code is very interop heavy I don&#x27;t think you gain a lot by using Clojurescript.<p>For a web <i>application</i> though interop code is going to be a tiny fraction of the overall code.