ScalaFiddle gist

Osc.scala

import math._
val (h, w) = (Page.canvas.height, Page.canvas.width)
var x = 0.0
// $FiddleStart
val graphs = Seq[(String, Double => Double)](
  ("red", sin),
  ("green", x => 2 - abs(x % 8 - 4)),
  ("blue", x => 3 * pow(sin(x / 12), 2) * sin(x))
)
// $FiddleEnd
.zipWithIndex
val count = graphs.size
dom.window.setInterval(() => {
  x = (x + 1) % w
  if (x == 0) Page.renderer.clearRect(0, 0, w, h)
  else for (((color, func), i) <- graphs) {
    val y = func(x/w * 75) * h/40 + h/count * (i+0.5)
    Page.renderer.fillStyle = color
    Page.renderer.fillRect(x, y, 3, 3)
  }
}, 10)

SierpinskiTriangle.scala

// $Template default
case class Pt(x: Double, y: Double)

val corners = Seq(
  Pt(Page.canvas.width/2, 0),
  Pt(0, Page.canvas.height),
  Pt(Page.canvas.width, Page.canvas.height)
)
var p = corners(0)
val (w, h) = (Page.canvas.height.toDouble, Page.canvas.height.toDouble)

dom.window.setInterval(() => for(_ <- 0 until 10){
  val c = corners(util.Random.nextInt(3))
  p = Pt((p.x + c.x) / 2, (p.y + c.y) / 2)
  val m = (p.y / h)
  val r = 255 - (p.x / w * m * 255).toInt
  val g = 255 - ((w-p.x) / w * m * 255).toInt
  val b = 255 - ((h - p.y) / h * 255).toInt
  Page.renderer.fillStyle = s"rgb($r, $g, $b)"
  Page.renderer.fillRect(p.x, p.y, 1, 1)
}, 10)

Test.scala

println("Hello world!")