draw-ball-bouncingball.js

// draws stuff to the screen
// allows us to separate calculations and drawing
function draw () {
  // clear the canvas and redraw everything
  ctx.clearRect(0, 0, canvas.width, canvas.height)

  // draw the ball (only object in this scene)
  ctx.beginPath()
  ctx.fillStyle = 'red'
  ctx.arc(
    ball.x, ball.y,
    ball.radius,
    0, Math.PI * 2
  )
  ctx.fill()
}