<canvas width="600" height="400"></canvas>
<script>
var pantalla = document.querySelector("canvas")
var pincel = pantalla.getContext("2d")
pincel.fillStyle = "lightgrey"
pincel.fillRect(0,0,600,400)
pincel.fillStyle = "green"
pincel.fillRect(0,0,200,400)
pincel.fillStyle = "red"
pincel.fillRect(400,0,200,400)
pincel.fillStyle = "yellow"
pincel.beginPath()
pincel.moveTo(300,200)
pincel.lineTo(200,400)
pincel.lineTo(400,400)
pincel.fill()
pincel.fillStyle = "blue"
pincel.beginPath()
pincel.arc(300,200,50,0,2*3.14)
pincel.fill()
</script>
