Running JS from JDK1.8 (mustache.js example and raw example with binding)

Mustache.scala

package nashorn

import javax.script.{Invocable, ScriptEngineManager, SimpleBindings}
import java.io.InputStreamReader
import scala.collection.JavaConverters._

object Mustache {
  private val engineManager = new ScriptEngineManager()
  val engine = engineManager.getEngineByName("nashorn")
  val invocable = engine.asInstanceOf[Invocable]

  engine.eval(new InputStreamReader(getClass.getResourceAsStream("mustache.min.js")))

  private val mustache = engine.eval("Mustache")

  def render(template: AnyRef, jsonObj: AnyRef) = invocable.invokeMethod(mustache, "render", template, jsonObj)

  private val JSON = engine.eval("JSON")

  def json(jsonString: String) = invocable.invokeMethod(JSON, "parse", jsonString)
}

object MustacheApp extends App {

  import Mustache._

  val template =
    """Email addresses of {{contact.name}}:
      |{{#contact.emails}}
      |- {{.}}
      |{{/contact.emails}}""".stripMargin

  val contactJson =
    """{
    "contact": {
      "name": "Mr A", "emails": ["[email protected]", "[email protected]"]
    }
   }"""

  val jsonObj = json(contactJson)

  println(render(template, jsonObj))

    // using play Json to create json blob here, same as commented out code

  import play.api.libs.json._
  val contactJson2=Json.obj("contact" -> Json.obj("name"-> "Mr B", "emails" ->List("[email protected]", "[email protected]") ))

//  val contactJson2 =
//    """{
//    "contact": {
//      "name": "Mr B", "emails": ["[email protected]", "[email protected]"]
//    }
//   }"""

  println(render(template, json(contactJson2.toString)))

  // if mustache isn't enough, you can always use raw Javascript

  val map=scala.collection.mutable.Map[String,Object]("greeting"->"Hello", "json"->json(contactJson2.toString))
  val bindings=new SimpleBindings(map.asJava)

  private val custom = engine.eval(
    """
      |var date=new Date
      |greeting+' '+json.contact.name+', it is now '+date;
    """.stripMargin, bindings)
  println(custom)
}

output.txt

Email addresses of Mr A:
- [email protected]
- [email protected]

Email addresses of Mr B:
- [email protected]
- [email protected]

Hello Mr B, it is now Fri Dec 30 2016 20:50:52 GMT+0000 (GMT)