nondeterministic/WorkerMain.scala

## index.html
<!DOCTYPE html>
<html>
<head>
    <title>WW PoC</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
</head>
<body>

<div id="root">
</div>

<script type="text/javascript" src="./target/scala-2.11/poc-fastopt.js"></script>
<script type="text/javascript">
Main().main();
</script>

</body>
</html>

## main.scala
package poc

import org.scalajs.dom
import org.scalajs.dom.raw.{Event, Worker}

import scalatags.JsDom.all._
import scala.scalajs.js.annotation.JSExport
import scala.scalajs.js

@JSExport("Main")
object Main {

  @JSExport
  def main(): Unit = {
    val worker = new Worker("worker.js")
    var x = 0
    val root = dom.document.getElementById("root")
    val click: js.Function1[Event, _] = (e: Event) => {
      x += 1
      if (x > 3) worker.postMessage("Testing")
    }

    root.appendChild(
      div(
        h1("Hello!"),
        button(id := "post", onclick := click, "Send message")
      ).render
    )

    worker.onmessage = (e: js.Any) => {
      root.appendChild(div(e.asInstanceOf[dom.MessageEvent].data.asInstanceOf[String]).render)
    }
    worker.postMessage("Testing")

    def nextAnimationFrame(time: Double): Unit = {
      dom.window.requestAnimationFrame(nextAnimationFrame _)
      // worker.postMessage(s"Time $time")
    }
    dom.window.requestAnimationFrame(nextAnimationFrame _)
  }
}

## worker.js
importScripts("./target/scala-2.11/poc-fastopt.js");
WorkerMain().main();

## WorkerMain.scala
package poc

import org.scalajs.dom

import scala.scalajs.js
import scala.scalajs.js.annotation.JSExport

@js.native
object WorkerGlobal extends js.GlobalScope {
  def addEventListener(`type`: String, f: js.Function): Unit = js.native
  def postMessage(data: js.Any): Unit = js.native
}

@JSExport("WorkerMain")
object WorkerMain {
  @JSExport
  def main(): Unit = {
    WorkerGlobal.addEventListener("message", onMessage _ )
    WorkerGlobal.postMessage(s"Started")
  }

  val timeMessage = """Time.*""".r
  var count = 0

  def onMessage(msg: dom.MessageEvent) = {
    val s = msg.data.asInstanceOf[String]
    s match {
      case timeMessage() =>
        count += 1
        if(count % 600 == 0)
          WorkerGlobal.postMessage("60fps")
      case _ =>
        WorkerGlobal.postMessage(s"Received: $s")
    }
  }
}
	<!DOCTYPE html>
	<html>
	<head>
	<title>WW PoC</title>
	<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
	</head>
	<body>

	<div id="root">
	</div>

	<script type="text/javascript" src="./target/scala-2.11/poc-fastopt.js"></script>
	<script type="text/javascript">
	Main().main();
	</script>

	</body>
	</html>
	package poc

	import org.scalajs.dom
	import org.scalajs.dom.raw.{Event, Worker}

	import scalatags.JsDom.all._
	import scala.scalajs.js.annotation.JSExport
	import scala.scalajs.js

	@JSExport("Main")
	object Main {

	@JSExport
	def main(): Unit = {
	val worker = new Worker("worker.js")
	var x = 0
	val root = dom.document.getElementById("root")
	val click: js.Function1[Event, _] = (e: Event) => {
	x += 1
	if (x > 3) worker.postMessage("Testing")
	}

	root.appendChild(
	div(
	h1("Hello!"),
	button(id := "post", onclick := click, "Send message")
	).render
	)

	worker.onmessage = (e: js.Any) => {
	root.appendChild(div(e.asInstanceOf[dom.MessageEvent].data.asInstanceOf[String]).render)
	}
	worker.postMessage("Testing")

	def nextAnimationFrame(time: Double): Unit = {
	dom.window.requestAnimationFrame(nextAnimationFrame _)
	// worker.postMessage(s"Time $time")
	}
	dom.window.requestAnimationFrame(nextAnimationFrame _)
	}
	}
	importScripts("./target/scala-2.11/poc-fastopt.js");
	WorkerMain().main();