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Chas Emerick April 01, 2014
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lein-cljsbuild

This is a Leiningen plugin that makes it quick and easy to automatically compile your ClojureScript code into Javascript whenever you modify it. It's simple to install and allows you to configure the ClojureScript compiler from within your project.clj file.

Beyond basic compiler support, lein-cljsbuild can optionally help with a few other things:

The latest version of lein-cljsbuild is 1.0.3. See the release notes here.

Requirements

The lein-cljsbuild plugin works with Leiningen version 2.1.2 or higher.

Installation

You can install the plugin by adding lein-cljsbuild to your project.clj file in the :plugins section:

(defproject lein-cljsbuild-example "1.2.3"
  :plugins [[lein-cljsbuild "1.0.3"]])

In addition, you should add an explicit ClojureScript dependency to your project, like this:

:dependencies [[org.clojure/clojurescript "0.0-XXXX"]]

lein-cljsbuild will add a dependency to your project if it doesn't already contain one, but that functionality will not remain for long. The latest version of lein-cljsbuild currently requires a minimum of ClojureScript 0.0-2197.

Just Give Me a Damned Example Already!

See the example-projects directory for a couple of simple examples of how to use lein-cljsbuild. The simple project shows a dead-simple "compile only" configuration, which is a good place to start. The advanced project contains examples of how to use the extended features of the plugin.

Also, see the sample.project.clj file for an exhaustive list of all options supported by lein-cljsbuild.

Basic Configuration

The lein-cljsbuild configuration is specified under the :cljsbuild section of your project.clj file. A simple project might look like this:

(defproject lein-cljsbuild-example "1.2.3"
  :plugins [[lein-cljsbuild "1.0.3"]]
  :cljsbuild {
    :builds [{
        ; The path to the top-level ClojureScript source directory:
        :source-paths ["src-cljs"]
        ; The standard ClojureScript compiler options:
        ; (See the ClojureScript compiler documentation for details.)
        :compiler {
          :output-to "war/javascripts/main.js"  ; default: target/cljsbuild-main.js
          :optimizations :whitespace
          :pretty-print true}}]})

For an exhaustive list of the configuration options supported by lein-cljsbuild, see the sample.project.clj file.

Basic Usage

Once the plugin is installed, you can build the ClojureScript once:

$ lein cljsbuild once

Or you can have lein-cljsbuild watch your source files for changes and automatically rebuild them. This is recommended for development, as it avoids the time-consuming JVM startup for each build:

$ lein cljsbuild auto

To delete all of the JavaScript and ClojureScript files that lein-cljsbuild automatically generated during compilation, run:

$ lein cljsbuild clean

If you've upgraded any libraries, you probably want to run lein cljsbuild clean afterward.

Hooks

Some common lein-cljsbuild tasks can hook into the main Leiningen tasks to enable ClojureScript support in each of them. The following tasks are supported:

$ lein compile
$ lein clean
$ lein test
$ lein jar

To enable ClojureScript support for these tasks, add the following entry to your project configuration:

:hooks [leiningen.cljsbuild]

Note that by default the lein jar task does not package your ClojureScript code in the JAR file. This feature needs to be explicitly enabled by adding the following entry to each of the :builds that you want included in the JAR file. lein uberjar derives its behavior from lein jar and will include the ClojureScript as well if enabled.

:jar true

Multiple Build Configurations

If the :builds sequence contains more than one map lein-cljsbuild will treat each map as a separate ClojureScript compiler configuration, and will build all of them in parallel:

(defproject lein-cljsbuild-example "1.2.3"
  :plugins [[lein-cljsbuild "1.0.3"]]
  :cljsbuild {
    :builds [
      {:source-paths ["src-cljs-main"]
       :compiler {:output-to "main.js"}
      {:source-paths ["src-cljs-other"]
       :compiler {:output-to "other.js"}}]})

This is extremely convenient for doing library development in ClojureScript. This allows cljsbuild to compile in all four optimization levels at once, for easier testing, or to compile a test suite alongside the library code.

You can optionally assign an ID to a build configuration and build only that one:

(defproject lein-cljsbuild-example "1.2.3"
  :plugins [[lein-cljsbuild "1.0.3"]]
  :cljsbuild {
    :builds [
      {:source-paths ["src-cljs-main"]
       :compiler {:output-to "main.js"}}
      {:id "other"
       :source-paths ["src-cljs-other"]
       :compiler {:output-to "other.js"}}]})
$ lein cljsbuild auto other

If you want IDs for all of your build configurations, you can specify them as a map instead of a vector:

(defproject lein-cljsbuild-example "1.2.3"
  :plugins [[lein-cljsbuild "1.0.3"]]
  :cljsbuild {
    :builds {
      :main
      {:source-paths ["src-cljs-main"]
       :compiler {:output-to "main.js"}}
      :other
      {:source-paths ["src-cljs-other"]
       :compiler {:output-to "other.js"}}}})

You can also build multiple configurations at once:

$ lein cljsbuild auto main other

See the example-projects/advanced directory for a working example of a project that uses this feature.

REPL Support

Lein-cljsbuild has built-in support for launching ClojureScript REPLs in a variety of ways. See the REPL documentation for more details.

Testing Support

Lein-cljsbuild has built-in support for running external ClojureScript test processes. See the testing documentation for more details.

ClojureScript Version

After configuring lein-cljsbuild, lein deps will fetch a known-good version of the ClojureScript compiler. You can use a different version of the compiler via a local clone of the ClojureScript git repository. See the wiki for details.

License

Source Copyright © Evan Mezeske, 2011-2013. Released under the Eclipse Public License - v 1.0. See the file COPYING.

Contributors

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