example/index.html

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>jQuery Time Duration Picker Example</title>
  <link rel="stylesheet" type="text/css" href="https://code.jquery.com/ui/1.13.1/themes/black-tie/jquery-ui.css">
  <style>
    body {
      padding: 10px;
    }
    input[type="text"] {
      font-size: 18px;
    }
  </style>
</head>
<body>
  <form>
    <input type="text" readonly="readonly" id="widget" placeholder="Click here..." size="100" style="text-align: center;" />
    <input type="hidden" name="duration" value="PT3H25M45S" id="duration" />
    <input type="hidden" name="seconds" value="12345" id="seconds" />
  </form>

  <script src="https://code.jquery.com/jquery-3.6.0.min.js" integrity="sha256-/xUj+3OJU5yExlq6GSYGSHk7tPXikynS7ogEvDej/m4=" crossorigin="anonymous"></script>
  <script src="https://code.jquery.com/ui/1.13.0/jquery-ui.min.js" integrity="sha256-hlKLmzaRlE8SCJC1Kw8zoUbU8BxA+8kR3gseuKfMjxA=" crossorigin="anonymous"></script>
  <script type="text/javascript" src="../src/jquery-time-duration-picker.js"></script>
  <script>
    $(function() {
      $('#widget').timeDurationPicker({
        seconds: true,
        defaultValue: function() {
          // The function must return either a String in ISO 8601 format (preferable)
          // (see https://en.wikipedia.org/wiki/ISO_8601#Durations),
          // or a Number - number of seconds

          return $("#duration").val(); // return parseInt($('#seconds').val(), 10);
        },
        onSelect: function(element, seconds, duration, text) {
          $('#seconds').val(seconds); // Number of seconds
          $('#duration').val(duration); // ISO 8601 (PnYnMnDTnHnMnS)
          $('#widget').val(text); // Human-readable duration
        }
      });
    });
  </script>
</body>
</html>