p5.js Animation

sketch.js

function setup() {
  createCanvas(windowWidth, windowHeight);
  colorMode(HSB, 360, 100, 100, 100);
  locationX = width / 2;
  locationY = height / 2;
  velocityX = random(-50, 50);
  velocityY = random(-50, 50);
}

function draw() {
  background(0);
  noStroke();
  fill(0, 100, 100, 100);
  circle(locationX, locationY, 50);
  locationX = locationX + velocityX;
  locationY = locationY + velocityY;
  if (locationX < 0 || locationX > width) {
    velocityX = velocityX * -1;
  }
  if (locationY < 0 || locationY > height) {
    velocityY = velocityY * -1;
  }
}