let y = 200;

let xspeed = 4;

let yspeed = -3;

​

function setup() {

  createCanvas(600, 400);

}

​

function draw() {

  background(0);

  move();

  bounce();

  display();

}

​

function bounce() {

  if (x > width || x < 0) {

    xspeed = xspeed * -1;

  }

​

  if (y > height || y < 0) {

    yspeed = yspeed * -1;

  }

}

​

function display() {

  stroke(255);

  strokeWeight(4);

  fill(200, 0, 200);

  ellipse(x, y, 24, 24);

}

​

function move() {

  x = x + xspeed;

  y = y + yspeed;

}

​