GregorianDate
external class GregorianDate(var year: Int = definedExternally, var month: Int = definedExternally, var day: Int = definedExternally, var hour: Int = definedExternally, var minute: Int = definedExternally, var second: Int = definedExternally, var millisecond: Int = definedExternally, var isLeapSecond: Boolean = definedExternally)(source)
Represents a Gregorian date in a more precise format than the JavaScript Date object. In addition to submillisecond precision, this object can also represent leap seconds.