custom list – Uncaught error Fullcalendar is not a function

I am using FullCalendar v3.10.2 and trying to run a script to prevent mutiple day selection. I searched and found that the fullcalendar function is not recognized. I am not sure what to do. My script is as follows(I have mentioned the html tags first which isbeing used in a separate file):

”’

$(function(){

var date = new Date();
var d = date.getDate();
var m = date.getMonth();
var y = date.getFullYear();

$(‘#calendar’).fullCalendar({

   selectable: true,
  selectHelper: true,
  editable: true,
  defaultView: 'agendaMonth',

  select: function (start, end) {
      var mEnd = $.fullCalendar.moment(end);
      var mStart = $.fullCalendar.moment(start);

      if (mEnd.isAfter(mStart, 'day')) {
          $('#calendar').fullCalendar('unselect');
      } else {
          $('#calendar').fullCalendar('renderEvent', {
              start: mStart,
              end: mEnd,
              allDay: false
          },
          true // stick the event
          );
          $('#calendar').fullCalendar('unselect');
      }
  }

});
});”’