Question

ClojureScript libraries are published to maven repositories just like Clojure. Most commonly they are published to Clojars but all other standard maven repositories work too.

shadow-cljs itself does not have direct support for publishing but since ClojureScript libraries are just uncompiled source files published in a JAR (basically just a ZIP compressed file) any common tool that is able to publish to maven will work. (eg. mvn, gradle, lein, etc). No extra compilation or other steps are required to publish. The ClojureScript compiler and therefore shadow-cljs is not involved at all.

17.1. Leiningen

There are a variety of options to publish libraries and I currently recommend Leiningen. The setup is very straightforward and doesn’t require much configuration at all.

Important

This does not mean that you have to use Leiningen during development of the library itself. It is recommended to just use Leiningen for publishing but use shadow-cljs normally otherwise. You’ll only need to copy the actual :dependencies definition once you publish. Remember to keep development related dependencies out though.

Assuming you are already using the recommended project structure where all your primary sources are located in src/main you can publish with a very simple project.clj.

(defproject your.cool/library "1.0.0"
  :description "Does cool stuff"
  :url "https://the.inter.net/wherever"
  ;; this is optional, add what you want or remove it
  :license {:name "Eclipse Public License"
            :url "http://www.eclipse.org/legal/epl-v10.html"}
  :dependencies
  ;; always use "provided" for Clojure(Script)
  [[org.clojure/clojurescript "1.10.520" :scope "provided"]
   [some.other/library "1.0.0"]]
  :source-paths
  ["src/main"])

This will generate the required pom.xml and put all sources from src/main into the published .jar file. All you need to run is lein deploy clojars to publish it. When doing this for the first time you’ll first need to setup proper authentication. Please refer to the official Leiningen and Clojars documentation on how to set that up.

17.1.1. Disable JAR Signing

Leiningen defaults to signing libraries via GPG before publishing which is a good default but given that this can be a hassle to setup and not many people are actually verifying the signatures you can disable that step via adding a simple :repositories config to the project.clj.

(defproject your.cool/library "1.0.0"
  ...
  :repositories
  {"clojars" {:url "https://clojars.org/repo"
              :sign-releases false}}
  ...)

17.1.2. Keep your JAR clean

If you write tests or user other development related code for your library make sure to keep them in src/dev or src/test to avoid publishing them together with the library.

Also avoid generating output to resources/* since Leiningen and other tools may include those files into the .jar which may cause problems for downstream users. Your .jar should ONLY contains the actual source files, no compiled code at all.

Important

You can and should verify that everything is clean by running lein jar and inspecting the files that end up in it via jar -tvf target/library-1.0.0.jar.

17.2. Declaring JS dependencies

Please note that currently only shadow-cljs has a clean automatic interop story with npm. That may represent a problem for users of your libraries using other tools. You may want to consider providing a CLJSJS fallback and/or publishing extra documentation for webpack related workflows.

You can declare npm dependencies directly by including a deps.cljs with :npm-deps in your project (eg. src/main/deps.cljs).

Example src/main/deps.cljs

{:npm-deps {"the-thing" "1.0.0"}}

You can also provide extra :foreign-libs definitions here. They won’t affect shadow-cljs but might help other tools.

See https://clojurescript.org/reference/packaging-foreign-deps for more info.