function setup() {

  createCanvas(400, 400);

  for (let i = 0; i < 5; i++) {

    r = random(10, 15);

    circles[i] = new Circle(random(r, width - r), random(r, height - r), r);

  }

}

​

function switch_circles(c) {

  for (let rest of circles) {

      if (c !== rest && c.intersects(rest)) {

        c.dir_x *= -1;

        c.dir_y *= -1;

        rest.dir_x *= -1;

        rest.dir_y *= -1;

        let temp_color = c.color;

        c.color = rest.color;

        rest.color = temp_color;

      }

    }

}

​

function draw() {

  background(0);

  for (let c of circles) {

    c.draw();

    c.move();

    switch_circles(c);

  }

}