Auto-buildingλ︎

The ClojureScript compiler supports incremental compilation. It's convenient to have the ClojureScript compiler watch a directory and recompile as needed. Let's make a new helper script watch.clj:

(require 'cljs.build.api)

(cljs.build.api/watch "src"
  {:main 'hello-world.core
   :output-to "out/main.js"})

Let's start auto building:

java -cp cljs.jar:src clojure.main watch.clj

You should see output like the following:

Building ...
Reading analysis cache for jar:file:/.../cljs.jar!/cljs/core.cljs
Analyzing src/hello_world/core.cljs
... done. Elapsed 1.425505401 seconds

Edit src/hello_world/core.cljs. You should see recompilation output.

Terminate auto building (using Ctrl-C) before proceeding to the next section.

Further Reading: While not required for the remainder of the Quick Start, it's highly recommended that you familiarize yourself with basics of Google Closure Library. Many simple errors can be avoided by reinforcing your understanding of how Closure Library works.