var startButton;

​

function setup() {

  createCanvas(400, 100);

  textAlign(CENTER);

  setInterval(timer, 1000);

}

​

function draw() {

  background(220);

  if (timerValue >= 10) {

    text("0:" + timerValue, width/ 2, height/ 2);

  }

  if (timerValue < 10) {

    text('0:0' + timerValue, width/ 2, height/ 2);

  }

  if (timerValue == 0) {

    text('game over', width/ 2, height/ 2 + 15);

  }

}

​

function timer() {

  if (timerValue > 0) {

    timerValue--;

  }

}