The dayOfWeek() method returns the day of week for the specified date.
DayPilot.Date.dayOfWeek();
A number specifying the day of week (0 = Sunday, 1 = Monday, 2 = Tuesday, 3 = Wednesday, 4 = Thursday, 5 = Friday, 6 = Saturday)
var today = DayPilot.Date.today().dayOfWeek();