var snakeY = 200;

function setup() {

  createCanvas(400, 400);

}

​

function draw() {

  background(0, 0, 0);

  fill("white");

  ellipse(snakeX, snakeY, 25, 25);

  //Key Commands

  if (keyIsPressed) {

    if (key === "d") {

      snakeX = snakeX + 1;

    }

    if (key === "a") {

      snakeX = snakeX - 1;

    }

    if (key === "w") {

      snakeY = snakeY - 1;

    }

    if (key === "s") {

      snakeY = snakeY + 1;

    }

  }

  //Constraints

  if (snakeX < 12.5) {

    snakeX = 12.5;

  }

  if (snakeX > 387.5) {

    snakeX = 387.5;

  }

  if (snakeY < 12.5) {

    snakeY = 12.5;

  }

  if (snakeY > 387.5) {

    snakeY = 387.5;

  }

  //Square Spawn

  square(random(x), random(y),20);

}

​