import cats.effect.concurrent.Deferred
import cats.effect.implicits._
import cats.effect.{ConcurrentEffect, IO}
import cats.implicits._
import org.scalajs.dom.html.Image
import org.scalajs.dom.{document, Event}

def loadImage[F[_]](url: String)(implicit F: ConcurrentEffect[F]): F[Boolean] =
  for {
    promise <- Deferred[F, Boolean]
    image <- F.delay(document.createElement("img").asInstanceOf[Image])
    register = { (event: String, result: Boolean) =>
      val listener = (_: Event) =>
        promise.complete(result).runAsync(_ => IO.unit).unsafeRunSync()
      F.delay(image.addEventListener(event, listener))
    }
    _ <- register("load", true)
    _ <- register("error", false)
    _ <- F.delay(image.src = url)
    result <- promise.get
  } yield result