SBT: Use %%% to import Scala.js and Scala-Native libraries

I was just reminded when reading this article that you have to use three % symbols when adding Scala.js and Scala-Native library dependencies in sbt. Specifically you’ll find that this libraryDependencies line does not work for adding a Scala.js and Scala-Native library dependency:

"com.github.scopt" %% "scopt" % "3.6.0"       // ERROR, DOESN’T WORK

This is the correct sbt syntax for Scala.js and Scala-Native libraries:

+= "com.github.scopt" %%% "scopt" % "3.6.0"   // WORKS

As the author of that article notes, this syntax is equivalent to this build.sbt line:

"com.github.scopt" % "scopt_native0.2_2.11" % "3.6.0"

Again I underlined the relevant syntax in that example.

If you’re trying to add a Scala.js or Scala-Native library dependency to an sbt build.sbt file, I hope this example is helpful.