let y = 0;

let xSpeed = 10;

let ySpeed = 5;

let color;

let bgColor;

​

function setup() {

  createCanvas(400, 400);

  color = [random(255), random(255), random(255)];

  bgColor = [random(255), random(255), random(255)];

}

​

function draw() {

  background(bgColor);

  fill(color);

  ellipse(x, y, 50, 50);

​

  x += xSpeed;

  y += ySpeed;

​

  if (x > width || x < 0) {

    xSpeed = -xSpeed;

    color = [random(255), random(255), random(255)];

    if (x > width || x < 0) {

        bgColor = [random(255), random(255), random(255)];

    }

  }

​

  if (y > height || y < 0) {

    ySpeed = -ySpeed;

    color = [random(255), random(255), random(255)];

    if (y > height || y < 0) {

        bgColor = [random(255), random(255), random(255)];

    }

  }

}

​