​

let locn;

let velocity;

let maxspeed = 10;

​

function setup() {

  createCanvas(800, 800);

  locn = createVector(250, 250);

  velocity = createVector(5, -5);

}

​

function draw() {

  background(120);

  velocity.limit(maxspeed); // set max velocity

  locn.add(velocity);

​

  ellipse(locn.x, locn.y, 10, 10);

  checkBounds();

}

​

function checkBounds() {

  if ((locn.x > width) || (locn.x < 0)) {

    velocity.x = velocity.x * -1;

  }

  if ((locn.y > height) || (locn.y < 0)) {

    velocity.y = velocity.y * -1;

  }

}