The monthNamesShort property (string[]) defines the abbreviated month names used by the locale, from January through December.
DayPilot.Locale.monthNamesShort['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec']The array should contain 12 items in calendar order, starting with January.
It is used for the "MMM" date formatting pattern in DayPilot.Date.toString().
const locale = DayPilot.Locale.find("en-us");
console.log(locale.monthNamesShort);