JavaScript | Countdown Timer

countDownTimer.js

// Countdown timer script, after 25secs it will add class on the body class="stop-animations"
// and clear the intervar. Timer value (60 * 1 = 1 minute)
function startTimer(duration, display, isRunning) {
  if (!!isRunning) {
    var timer = duration, minutes, seconds;
    var interval = setInterval(function () {
      minutes = parseInt(timer / 60, 10);
      seconds = parseInt(timer % 60, 10);
      minutes = minutes < 10 ? "0" + minutes : minutes;
      seconds = seconds < 10 ? "0" + seconds : seconds;
      display.innerHTML = minutes + ":" + seconds;
      if (--timer < 0) {
        timer = 0;
        document.getElementsByTagName('body')[0].className+=' stop-animations';
        clearInterval(interval);
      }
    }, 1000);
  }
}

var time = 25, display = document.getElementById("count");
startTimer(time, display, true);