The parser combinator library is currently not included in Scala.js.
However, for Scala 2.11.0-M8, we have a fork of the scala-parser-combinators repo with a scalajs branch where we build it for Scala.js: https://github.com/sjrd/scala-parser-combinators/tree/scalajs
It's still at the proof of concept stage. When 2.11.0 final is out (which will be any week now), we'll update this repo and publish the artifact so that they can be used by user projects. Currently, you can use it if you clone the repo and publishLocal
it yourself (and you use Scala 2.11.0-M8 in your Scala.js project).
Sorry for the inconvenience. It'll get better soon.