let xspeed=3;

​

function setup() {

  createCanvas(400,400);

}

​

function draw() {

  background(220);

  move();

  display();

  bounce();

}

  //Always move the ball

function move(){

  xspeed=bounce(x,0,width,xspeed);

  x=x+xspeed;

}

​

function bounce(pos,low,high,speed){

  if(pos<low||pos>high){

    return speed=-speed;

  } else{

    return speed;

  }

}

function display(){

  ellipse(x, height/2, 50, 50);

}

​