how to output individual files to a specified directory for cljsbuild

Question

Using cljsbuild, I can compile all my .cljs files to one file. However, I wish to be able to pick a directory for output and have each .cljs file compile into its own .js file. How can this be specified?

Answer 1

You can use 'multiple build configurations': cljsbuild accepts a vector of configurations for :builds key, each element of which defines rules for compiling separate .js file (more info could be found in lein-cljsbuild README). Simple example:

:cljsbuild 
{:builds 
 [;; Config for first .js file
  {:source-paths ["dir-with-cljs-for-first-js"]
   :compiler {:output-to "dir-for-js/first.js"}
  ;; Config for second .js file
  {:source-paths ["dir-with-cljs-for-second-js"]
   :compiler {:output-to "dir-for-js/second.js"}}]} 

Answer 2

You're looking for the :output-dir option. My cljsbuild looks like this:

:cljsbuild
  {:builds
   [{:id "dev"
     :source-paths ["src/cljs"]
     :compiler {:output-to  "resources/public/js/site.js"
                :output-dir "resources/public/js/out"
                :source-map true :optimizations :none }}
    {:id "main"
     :source-paths ["src/cljs"]
     :compiler {:pretty-print false
                :output-to "resources/public/js/site.js"
                :source-map "resources/public/js/site.js.map"
                :optimizations :advanced}}]}

With this config, and without site.js already compiled/up to date, lein cljsbuild once dev or lein cljsbuild auto dev will compile site.js, then see it's dependencies aren't compiled and go compile them, along with their sourcemaps. If site.js is compiled and up to date, cljsbuild will think there's nothing to be done and terminate before generating source maps, etc.

I also highly recommend lein figwheel for cljs development, and remember to enable sourcemaps.