Can I put a function in Fullcalendar’s headerToolbar item?

headerToolbar:{
  left:'prevYear prev today next nextYear',
  center:'title',
  right:'dayGridMonth,dayGridWeek,timeGridDay,listMonth'
},
date : moment().format('YYYY-MM')

While making Fullcalendar, I suddenly became curious
When I press the prev button in the headerToolbar, I want to make the variable date a month ago. Can I make it so that the function can be executed when I press the prev button?

/admin/visit/schedule/month?managerId"+this.managerId+"&date="+this.date

In this way, when the month of the calendar is changed, the variable date is changed and I am trying to call the api using it.