let xchange = 1;

​

function setup() {

  createCanvas(400, 400);

} // end function setup()

​

function draw() {  

  background(220);

  ellipse(x, 100, 20, 20);

  fill(0, 0, 255);

  x = x + xchange;

  console.log("xchange = " + xchange)

​

  if (x > 200) {

    xchange = 0;

  }

}

​

​