var move = 2;

var s = 20;

​

function setup() {

  createCanvas(400, 400);

  rectMode(CENTER);

  background(0);

  noStroke();

  fill(255);

  x = width/2;

  y = height/2;

}

​

function draw() {

  background(0);

  if (keyCode == UP_ARROW) {

    y -= move;

  } else if (keyCode == DOWN_ARROW) {

    y += move;

  } else if (keyCode == LEFT_ARROW) {

    x -= move;

  } else if (keyCode == RIGHT_ARROW) {

    x += move;

  }

  if (x > width + s) x = -s;

  if (x < -s) x = width + s;

  if (y > height + s) y = -s;

  if (y < -s) y = height + s;

  rect(x, y, s, s);

}

​

​

​

​

​

​

​

​

​

​

​

​

​