Playing with Scala.js and a canvas (code)

Main.scala

import scala.scalajs.js.annotation.JSExport
import org.scalajs.dom
import scala.util.Random

object Main {
  @JSExport
  def main(args: Array[String]): Unit = {
    var canvas = dom.document.createElement("canvas")
                             .asInstanceOf[dom.html.Canvas]
    
    dom.document.body.appendChild(canvas)
    
    val height = dom.window.innerHeight.toInt
    val width = dom.window.innerWidth.toInt
    
    canvas.height = height
    canvas.width = width

    val ctx = canvas.getContext("2d")
                    .asInstanceOf[dom.CanvasRenderingContext2D]

    def reColor() = {
      val r = Random.nextInt(255)
      val g = Random.nextInt(255)
      val b = Random.nextInt(255)
      ctx.fillStyle = s"rgb($r, $g, $b)"
      ctx.fillRect(0, 0, width, height)
    }

    dom.window.setInterval(() => reColor, 1000)
  }
}