fullcalendar dynamically change default view based on screen width

I'm using fullcalendar and the below code works for me to render fullcalendar while also using turbolinks.

function eventCalendar() {
  return $('#event_calendar').fullCalendar({
    defaultView: 'agendaWeek',
    header: {
        left: 'prev,today,next',
        center: 'title',
        right: 'agendaDay,agendaWeek'
    },    
  });
};
function clearCalendar() {
  $('#event_calendar').fullCalendar('delete'); // In case delete doesn't work.
  $('#event_calendar').html('');
};
$(document).on('turbolinks:load', eventCalendar);
$(document).on('turbolinks:before-cache', clearCalendar)

However I want to dynamically changeView the defaultView based on screenWidth. Something like this, but it's not working for some reason:

if (window.innerWidth < 800) {
            $('#event_calendar').fullCalendar('changeView', 'agendaDay');
        }

or

if(window.innerWidth < 800){
    $('#event_calendar').fullCalendar('changeView', 'agendaDay');
}else{
    $('#event_calendar').fullCalendar('changeView', 'agendaWeek');
}

How can I adapt it to my calendar? Please help!

If by "dynamically change" you mean you want to change it when the user resizes their browser, then you need to listen for window resize.

$(window).resize(function() {
  if(window.innerWidth < 800){
    $('#event_calendar').fullCalendar('changeView', 'agendaDay');
  } else {
    $('#event_calendar').fullCalendar('changeView', 'agendaWeek');
  }
});

But also check your browser console for errors. It looks like as of version 4.0+ those views have been renamed see changelog so you may need to pass different view names like this:

$(window).resize(function() {
  if(window.innerWidth < 800){
    $('#event_calendar').fullCalendar('changeView', 'timeGridDay');
  } else {
    $('#event_calendar').fullCalendar('changeView', 'timeGridWeek');
  }
});