Nashorn Example

NashornExample.scala

import javax.script._

object NashornExample extends App {
  val ENGINE_NAME = "nashorn"
  val engine = new ScriptEngineManager()
    .getEngineByName(ENGINE_NAME)
    .asInstanceOf[ScriptEngine with Invocable]

  val fName = "func"
  val f = s"""function $fName(a, b) { return a + b; };"""
  engine.asInstanceOf[Compilable].compile(f).eval()

  val argments = Seq(1, 2) map { _.asInstanceOf[AnyRef] }
  val result = engine.invokeFunction(fName, argments: _*)
  println(s"result => $result")
}

object NashornTypingExample extends App {
  val ENGINE_NAME = "nashorn"
  val engine = new ScriptEngineManager()
    .getEngineByName(ENGINE_NAME)
    .asInstanceOf[ScriptEngine with Invocable with Compilable]

  case class User(id: Long, name: String)

  // use Scala type in JavaScript
  val fName = "f"
  val f =
    s"""
       |function $fName(user) {
       |  return "id: " + user.id() + ", name: " + user.name();
       |};
       |""".stripMargin
  engine.compile(f).eval()

  val result1 = engine.invokeFunction(fName, User(1, "alice"))
  println(s"result1 => $result1")

  // casting JavaScript result to Scala type 
  val gName = "g"
  val g =
    s"""
       |function $gName(id, name) {
       |  var User = Java.type("NashornTypingExample.User");
       |  return new User(id, name);
       |};
       |""".stripMargin

  engine.compile(g).eval()

  val result2 = engine.invokeFunction(gName, Seq(2, "bob") map {_.asInstanceOf[AnyRef]} :_*)
  println(s"result2 => $result2")
  println(s"result2 => ${result2.asInstanceOf[User].name}")
}

run result is below.

$ scalac NashornExample.scala
$ scala NashornExample
result => 3
$ scala NashornTypingExample
result1 => id: 1, name: alice
result2 => User(2,bob)
result2 => bob