Q:

How to use '%%%' in a Build.scala file

I'm getting familiar with using the '%%%' operator in a build.sbt file, but I don't understand how to use it in a build.scala file. I'm getting the following error:
value %%% is not a member of String

I'm guessing that I have to import the %%% somehow but I don't see how. I tried the following:
import org.scalajs.sbtplugin.ScalaJSPlugin._
import ScalaJSKeys._

A:

Edit: Since Scala.js 0.6.23, you need the following import:
import org.portablescala.sbtplatformdeps.PlatformDepsPlugin.autoImport._

Old answer for Scala.js < 0.6.23:
As documented here, the appropriate imports are
import org.scalajs.sbtplugin.ScalaJSPlugin
import org.scalajs.sbtplugin.ScalaJSPlugin.autoImport._

