<div id="countdown">
<script>
var timeleft = 15;
var downloadTimer = setInterval(function(){
  if(timeleft <= 0){
    clearInterval(downloadTimer);
    document.getElementById("countdown").innerHTML = "your file is ready";
  } else {
    document.getElementById("countdown").innerHTML = timeleft + " will download after";
  }
  timeleft -= 1;
}, 1000);</script>




<script type="text/javascript">
  var count = 15000; // Timer
  var redirect = "/"; // Target URL

  function countDown() {
    var timer = document.getElementById("timer"); // Timer ID
    if (count > 0) {
      count--;
      timer.innerHTML = "This page will redirect in " + count + " seconds."; // Timer Message
      setTimeout("countDown()", 1000);
    } else {
      window.location.href = redirect;
    }
  }
</script>
<div id="timer">
<script type="text/javascript">
          countDown();
        </script>
      </div>

  window.history.back();