<div id="calendar"></div>

document.addEventListener( 'DOMContentLoaded', () => {
  const calendarEl = document.getElementById( 'calendar' );
  const calendar = new FullCalendar.Calendar( calendarEl, {
    initialView: 'listWeek',
    events: function ( info, successCallback ) {
      successCallback(
        [
          {
            title: 'サンプル',
            start: new Date()
          }
        ]
      )

    }
  } );
  
  calendar.render();
} );