weekNumberCalculation

The method for calculating week numbers that are displayed with the weekNumbers setting.

<div class='spec' markdown='1'> String/Function, *default*:`"iso"` </div>

The default ("iso") causes ISO8601 week numbers.

You may also specify a function, which accepts a single native Date object and returns an integer week number. Since FullCalendar currently lacks a built-in internationlization system, this is only way to implement localized week numbers.