​

function setup() {

  createCanvas(400, 400);

  ball = new Ball();

  print(ball);

}

​

function draw() {

  stroke(200);

  ball.show();

  ball.move();

  ball.changeSize();

  ball.changeColour();

}

​

class Ball {

  constructor() {

    this.x = 200;

    this.y = 200;

    this.size = 10;

    this.colour = 255;

  }

  move() {

    if (this.x > 0 && this.x < 400 && this.y > 0 && this.y < 400) {

      this.x += random(-15, 15);

      this.y += random(-15, 15);

    } else {

      this.x = 200;

      this.y = 200;

    }

  }

  show() {

    fill(this.colour)

    circle(this.x, this.y, this.size);

  }

  changeSize() {

    this.size += random(-5, 5);

  }

  changeColour() {

    this.colour = color(random(0, 255));

  }

}

​