minimaxir/countdown.html

## countdown.html
<!DOCTYPE html>
<html>

<head>
  <meta charset="UTF-8">
  <title>A simple clock</title>

</head>

<body translate="no" >
  <div id="output"></div>

  <script src='https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.18.1/moment.min.js'></script>
  <script>
// https://stackoverflow.com/questions/901115/how-can-i-get-query-string-values-in-javascript
var urlParams;
(function () {
    var match,
        pl     = /\+/g,  // Regex for replacing addition symbol with a space
        search = /([^&=]+)=?([^&]*)/g,
        decode = function (s) { return decodeURIComponent(s.replace(pl, " ")); },
        query  = window.location.search.substring(1);
    urlParams = {};
    while (match = search.exec(query))
       urlParams[decode(match[1])] = decode(match[2]);
})();
var output = document.getElementById("output");
if (urlParams["style"]) output.setAttribute("style", urlParams["style"]);
if (urlParams["bodyStyle"]) document.body.setAttribute("style", urlParams["bodyStyle"]);
var c;
setInterval(
c = function() {
  // https://stackoverflow.com/questions/18623783/get-the-time-difference-between-two-datetimes
  var now  = moment();
  var targetTime = urlParams["targetTime"];

  var countdown = moment(targetTime).diff(now)

  if (countdown > 0) {
    var countdownText = moment.utc(countdown).format("HH:mm:ss");
  }
  else {
    var countdownText = "Now!"
  }
    output.innerText = countdownText;
}, 1000);
c();
  </script>
</body>
</html>
	<!DOCTYPE html>
	<html>

	<head>
	<meta charset="UTF-8">
	<title>A simple clock</title>

	</head>

	<body translate="no" >
	<div id="output"></div>

	<script src='https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.18.1/moment.min.js'></script>
	<script>
	// https://stackoverflow.com/questions/901115/how-can-i-get-query-string-values-in-javascript
	var urlParams;
	(function () {
	var match,
	pl = /\+/g, // Regex for replacing addition symbol with a space
	search = /([^&=]+)=?([^&]*)/g,
	decode = function (s) { return decodeURIComponent(s.replace(pl, " ")); },
	query = window.location.search.substring(1);
	urlParams = {};
	while (match = search.exec(query))
	urlParams[decode(match[1])] = decode(match[2]);
	})();
	var output = document.getElementById("output");
	if (urlParams["style"]) output.setAttribute("style", urlParams["style"]);
	if (urlParams["bodyStyle"]) document.body.setAttribute("style", urlParams["bodyStyle"]);
	var c;
	setInterval(
	c = function() {
	// https://stackoverflow.com/questions/18623783/get-the-time-difference-between-two-datetimes
	var now = moment();
	var targetTime = urlParams["targetTime"];

	var countdown = moment(targetTime).diff(now)

	if (countdown > 0) {
	var countdownText = moment.utc(countdown).format("HH:mm:ss");
	}
	else {
	var countdownText = "Now!"
	}
	output.innerText = countdownText;
	}, 1000);
	c();
	</script>
	</body>
	</html>