I'm not aware of a good reason to prefer ClojureScript+Node.js in general. Maybe if you wanted interop with a specific Node library, but otherwise, Clojure on the JVM will tend to have vastly better performance, and the tooling is better.
For example, until recently ClojureScript's :keywords were just strings under the hood and it required a string compare to test equality. Apparently this is no longer the case due to this commit 2 months ago: https://github.com/clojure/clojurescript/commit/2cef52840fcd... but it shows you the kind of stuff you might run into. In a recent talk I saw by David Nolen, the lead maintainer of the ClojureScript compiler, he brought up multimethod dispatch as something that can still be as much as 100 times slower than the JVM.
As a tooling example, Clojure gives you helpful errors if you initialize records the wrong way:
user=> (defrecord Thing [foo bar])
user.Thing
user=> (Thing. 1 2) ; correct usage
#user.Thing{:foo 1, :bar 2}
user=> (Thing. 1) ; wrong number of fields
CompilerException java.lang.IllegalArgumentException: No matching ctor found for class user.Thing, compiling:(/tmp/form-init7089728177345913731.clj:1:1)
user=> (Thing 1 2) ; forgetting the dot
RuntimeException Expecting var, but Thing is mapped to class user.Thing clojure.lang.Util.runtimeException (Util.java:219)
That's good! Especially if you're new to the language. You see where you messed up right away.
This should be a bug report against the CLJS compiler (edit: now it is[1]), and it's probably not that hard to fix. I could fix it. You could fix it. (The CLJS compiler is very approachable and needs contributors, by the way.) But, especially as a newbie, this kind of stuff can bite you. JVM Clojure is more polished.
Well that is pretty tempting! I would be inclined to contribute if I was working on some project where it made sense to use ClojureScript. Perhaps in a couple months when I start working on front end stuff I'll have the chance!
I wouldn't say that. In this case for instance it more or less just shoves java's error message in your face, you have to translate that back into the clojure you typed beforehand.
OK, I can see the case for that nitpick. Perhaps neither implementation is particularly "polished" in this regard, and the JVM one just happens to fail faster due to a statically-typed host environment. Polished or not, though, the end result is Clojure being more helpful when you make typos/newbie mistakes.
For example, until recently ClojureScript's :keywords were just strings under the hood and it required a string compare to test equality. Apparently this is no longer the case due to this commit 2 months ago: https://github.com/clojure/clojurescript/commit/2cef52840fcd... but it shows you the kind of stuff you might run into. In a recent talk I saw by David Nolen, the lead maintainer of the ClojureScript compiler, he brought up multimethod dispatch as something that can still be as much as 100 times slower than the JVM.
As a tooling example, Clojure gives you helpful errors if you initialize records the wrong way:
That's good! Especially if you're new to the language. You see where you messed up right away.But ClojureScript just silently gives you nils:
This should be a bug report against the CLJS compiler (edit: now it is[1]), and it's probably not that hard to fix. I could fix it. You could fix it. (The CLJS compiler is very approachable and needs contributors, by the way.) But, especially as a newbie, this kind of stuff can bite you. JVM Clojure is more polished.1. http://dev.clojure.org/jira/browse/CLJS-639