var v0 = ABS_DATESTRING($DateTime.Today,"yyyy/MM/dd")
var v1 = v0+" 09:00:00"
var time = new Date(v1);
var b = 30;
time.setMinutes(time.getMinutes()+b, time.getSeconds(), 0)
ABS_DATESTRING(time,"HH:mm:ss")
原文：http://www.cnblogs.com/zkx4213/p/5611572.html