Scala.js Node.js run process

run.scala

  def runProcess(command: String, cwd: Option[String], details: String = ""): Future[String] = {
    val msg = if (details == "") then s"Running command `${command}`" else s"${details}"
    println(s"${msg}...")
    val options = encodingBufferEncodingExe(BufferEncoding.utf8)
    cwd.foreach(cwdR => options.cwd = cwdR)
    val process = node_child_process.exec(command, options)
    var strBuilder = mutable.StringBuilder()
    process.stdout.asInstanceOf[typings.node.streamMod.Readable].on_data(nodeStrings.data, data => {
      strBuilder.append(data)
      println(s"cmd stdout: $data")
    })
    process.stderr.asInstanceOf[typings.node.streamMod.Readable].on_data(nodeStrings.data, data => {
      println(s"cmd stderr: $data")
    })

    val promise: Promise[String] = Promise[String]()
    process.on_exit(nodeStrings.exit, (code: Double | Null, signal: Signals | Null) => {
      val codeStr = Objects.toString(code)
      if (codeStr == "0") {
        println(s"Done: ${details}")
        promise.success(strBuilder.toString)
      } else {
        val message = s"Command exited with code ${codeStr}"
        println(message)
        promise.failure(new RuntimeException(message))
      }
    })
    promise.future
  }