countdown.html

<!DOCTYPE HTML>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
p {
  text-align: center;
  font-size: 60px;
  margin-top: 0px;
}
</style>
</head>
<body>

<p id="demo"></p>

<script>
// Set the date we're counting down to
var countDownDate = new Date("July 4, 2020 19:00").getTime();

// Update the count down every 1 second
var x = setInterval(function() {

  // Get today's date and time
  var now = new Date().getTime();

  // Find the distance between now and the count down date
  var distance = countDownDate - now;

  // Time calculations for days, hours, minutes and seconds
  var days = Math.floor(distance / (1000 * 60 * 60 * 24));
  var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
  var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
  var seconds = Math.floor((distance % (1000 * 60)) / 1000);
        function getlength(number) {
    return number.toString().length;
}

if (getlength(hours) == 1) {
hours = "0"+hours;
}
if (getlength(minutes) == 1) {
minutes = "0"+minutes;
}
if (getlength(seconds) == 1) {
seconds = "0"+seconds;
}
  // Output the result in an element with id="demo"
  document.getElementById("demo").innerHTML = days + " : " + hours + " : "
  + minutes + " : " + seconds + "";

  // If the count down is over, write some text
  if (distance < 0) {
    clearInterval(x);
    document.getElementById("demo").innerHTML = "Happy July Fourth!"
  }
}, 1000);
</script>

</body>
</html>