Trying to subtract 1.5 hours from a set time field in Acrobat

[Claudia280077979gsm]

I have a manually entered time field h:MM tt but I want it to populate another field but deducting 1.5 hours.

Example: "Day1startTime" is 8:00 am, minus 1.5 hours should autopopulate "Day1arrivalTime" 6:30am

Can someone please help me!

[Thom Parker]

Here's one technique that uses the date object. 

This code is for a custom valdate script on the "Day1startTime" field, where the time value is entered. 

var strArrTime = "";

var oTimeNow = util.scand("dd/mm/yy h:MM tt","01/01/23 " + event.value);

if(oTimeNow && !isNaN(oTimeNow.getTime()))
{
    oTimeNow.setMinutes(oTimeNow.getMinutes() - 90);
    strArrTime = util.printd("h:MM tt",oTimeNow);
}
this.getField("Day1arrivalTime").value = strArrTime;

[Claudia280077979gsm]

Thank you so much! That worked perfectly!

[Claudia280077979gsm]

Could you help me with one more thing?

Is it possible that the "Day1ArrivalTime" shows blank if there is no time in the Day1startTime? Right now if I don't enter a time the Arrival time automatically shows 10:30pm. (I guess it assumes that no entry on Day1start time is midnight).

Thanks again!

[try67]

Use this:

if (event.value=="") this.getField("Day1arrivalTime").value = "";

else {

// put Thom's code here

}