The getDay() method returns the day of the month as an integer from 1 to 31.
DayPilotDayPilot.Date.getDay()This method has no parameters.
Use this method to read the day-of-month component of the current DayPilot.Date value.
const date = new DayPilot.Date("2025-03-15T00:00:00");
const day = date.getDay();