Monix based Ajax

ajax.scala

object Ajax {
  def get(url: String, data: InputData = null, timeout: Int = 0,
      headers: Map[String, String] = Map.empty,
      withCredentials: Boolean = false, responseType: String = "") = {
    apply("GET", url, data, timeout, headers, withCredentials, responseType)
  }

  def post(url: String, data: InputData = null, timeout: Int = 0,
      headers: Map[String, String] = Map.empty,
      withCredentials: Boolean = false, responseType: String = "") = {
    apply("POST", url, data, timeout, headers, withCredentials, responseType)
  }

  def apply(
    method: String,
    url: String,
    data: InputData,
    timeout: Int,
    headers: Map[String, String],
    withCredentials: Boolean,
    responseType: String
  ): Task[dom.XMLHttpRequest] = {
    Task.create[dom.XMLHttpRequest] {
      case (s: Scheduler, c: Callback[dom.XMLHttpRequest]) =>
        val req = new dom.XMLHttpRequest()

        req.onreadystatechange = { (e: dom.Event) =>
          if (req.readyState.toInt == 4) {
            if ((req.status >= 200 && req.status < 300) || req.status == 304)
              c.onSuccess(req)
            else
              c.onError(AjaxException(req))
          }
        }
        req.open(method, url)
        req.responseType = responseType
        req.timeout = timeout
        req.withCredentials = withCredentials
        headers.foreach(x => req.setRequestHeader(x._1, x._2))
        if (data == null)
          req.send()
        else
          req.send(data)

        def onSuccess(value: T): Unit
        def onError(ex: Throwable): Unit

        monix.Cancelable.empty
    }
  }
}