let myX = 0;

​

//initialize variable for speed

let mySpeed = 1;

​

function setup() {

  createCanvas(400, 400);

}

​

function draw() {

  background(220);

  //use variable for x

  circle(myX, 200,200);

  //reverse at right and left boundary

  if(myX > width || myX < 0){

    mySpeed = mySpeed*-1;

  }

  //add speed

  myX += mySpeed;

  //set size of text

  textSize(20);

  //display x location as text

  text("x = " + myX, myX - 30, 200);

}