sbt-play-scalajs is a SBT plugin which allows you to use Scala.js along with Play Framework. It uses the sbt-web and scala-js plugins.

Specify the sbt version in project/build.properties which needs to be 0.13.5 or higher:

sbt.version=0.13.5

Add the sbt plugin to the project/plugins.sbt file along with Play! and Scala.js:

addSbtPlugin("com.vmunier" % "sbt-play-scalajs" % "0.2.6")

addSbtPlugin("com.typesafe.play" % "sbt-plugin" % "2.4.0")

addSbtPlugin("org.scala-js" % "sbt-scalajs" % "0.6.3")

Lastly, write the following configuration in build.sbt:

import sbt.Project.projectToRef

lazy val jsProjects = Seq(js)

lazy val jvm = project.settings(
  scalaJSProjects := jsProjects,
  pipelineStages := Seq(scalaJSProd)).
  enablePlugins(PlayScala).
  aggregate(jsProjects.map(projectToRef): _*)

lazy val js = project.enablePlugins(ScalaJSPlugin, ScalaJSPlay)

There are two auto-plugins: ScalaJSPlay and PlayScalaJS. The workflow is the following:

• ScalaJSPlay plugin is enabled in Scala.js projects.
• PlayScalaJS is added to Play project. It is build on top of SbtWeb plugin and can also add itself automaticly to all projects that have SbtWeb enabled.
• Scala.js projects are collected in the scalaJSProjects setting key of the Play project.
• When compilation or testing takes place, then the PlayScalaJS plugin runs all required tasks on scalaJSProjects projects, copies the output to Play assets and takes care about source maps.

To see the plugin in action, you can clone and run this simple example application.

• Use the scalaJSProjects setting key to attach several Scala.js projects to the Play! project
• The scalaJSProd pipeline task generates the optimised javascript when running start, stage and dist
• Source Maps is disabled in production by default to prevent your users from seeing the source files. But it can easily be enabled in production too by setting (emitSourceMaps in fullOptJS) := true in the Scala.js projects.
• Use the sourceMapsDirectories setting on a Scala.js project to specify additional directories containing Scala files needed for Source Maps. You would typically use this setting when your Scala.js project depends on another Scala.js project.