JavaScript FullCalendar demo timeZone確認 #JavaScript

JavaScript の FullCalendar の demo をもとに timeZone を確認
demo は以下より取得
https://fullcalendar.io/docs/getting-started
<!DOCTYPE html>
<html>
<head>
<meta charset='utf-8' />
<link href='../packages/core/main.css' rel='stylesheet' />
<link href='../packages/daygrid/main.css' rel='stylesheet' />
<script src='../packages/core/main.js'></script>
<script src='../packages/interaction/main.js'></script>
<script src='../packages/daygrid/main.js'></script>
<script>

  document.addEventListener('DOMContentLoaded', function() {
    var calendarEl = document.getElementById('calendar');

    var calendar = new FullCalendar.Calendar(calendarEl, {
      plugins: [ 'interaction', 'dayGrid' ],
      defaultDate: '2019-06-12',
      editable: true,
      eventLimit: true, // allow "more" link when too many events
      <!-- timeZone: 'local', -->
      timeZone: 'UTC',
      events: [
        {
          title: 'All Day Event',
          start: '2019-06-01T23:00:00Z',
          end: '2019-06-05T15:59:59Z',
        },
        {
          title: 'Long Event',
          start: '2019-06-07',
          end: '2019-06-10'
        },
        {
          groupId: 999,
          title: 'Repeating Event',
          start: '2019-06-09T16:00:00'
        },
        {
          groupId: 999,
          title: 'Repeating Event',
          start: '2019-06-16T16:00:00'
        },
        {
          title: 'Conference',
          start: '2019-06-11',
          end: '2019-06-13'
        },
        {
          title: 'Meeting',
          start: '2019-06-12T10:30:00',
          end: '2019-06-12T12:30:00'
        },
        {
          title: 'Lunch',
          start: '2019-06-12T12:00:00'
        },
        {
          title: 'Meeting',
          start: '2019-06-12T14:30:00'
        },
        {
          title: 'Happy Hour',
          start: '2019-06-12T17:30:00'
        },
        {
          title: 'Dinner',
          start: '2019-06-12T20:00:00'
        },
        {
          title: 'Birthday Party',
          start: '2019-06-13T07:00:00'
        },
        {
          title: 'Click for Google',
          start: '2019-06-23T07:00:00Z',
          end: '2019-06-27T07:00:00Z'
        }
      ]
    });

    calendar.render();
  });

</script>
<style>

  body {
    margin: 40px 10px;
    padding: 0;
    font-family: Arial, Helvetica Neue, Helvetica, sans-serif;
    font-size: 14px;
  }

  #calendar {
    max-width: 900px;
    margin: 0 auto;
  }

</style>
</head>
<body>

  <div id='calendar'></div>

</body>
</html>