Scala.js Asynchronous REST call (Ajax) demo with JSON parsing - http://www.scala-js-fiddle.com/gist/484e6ca68976aadb2cac63b55069acd8

Main.scala

import util._
import dom.ext._
import scala.scalajs.concurrent.JSExecutionContext.Implicits.runNow

object ScalaJSExample extends js.JSApp{
  def main(): Unit = {
    val url =
    "http://jsonplaceholder.typicode.com/posts/1"
    val f=Ajax.get(url)
    f.onComplete{ 
      case Success(xhr) =>
        val json=js.JSON.parse(xhr.responseText)
        val title=json.title.toString
        val body=json.body.toString
        println(div(
          h1(title),
          p(body)).render)
      case Failure(e) => println(e.toString)
    }
  }
}