let ySpeed = 3;

let xLocation = 200;

let yLocation = 200;

let ballColor = "#000000";

function setup() {

  createCanvas(400, 400);

}

​

function draw() {

  background(220);

  xLocation+=xSpeed;

  yLocation +=ySpeed;

  if (xLocation + 25 > 400 || xLocation-25 < 0)

    {

      xSpeed = -xSpeed;

      fill(ballColor);

    }

  if (yLocation + 25 > 400 || yLocation-25 < 0)

    {

      ySpeed = -ySpeed;

       fill(ballColor);

    }

  else

    {

       fill("#ffffff");

    }

  circle(xLocation, yLocation, 50);

}