Using getDate in input field, and displaying daysLeftUntil in another field...

[jpcsolutions]

I am trying to use JS in an adobe form I created. I have a date field in which the user enters the current date. Then, in another field, the days left until the end of the year are displayed. I can do this great in HTML, but behavior in Acrobat isn't quite the same.

Here's what I have so far, but applying it proves difficult.

function DayDiff(StartDate)
{
	var TYear=CurrentDate.getTime();
        var TDay=new Date("January, 01, 2014");
        TDay.getFullYear(TYear);
        var DayCount=(TDay-StartDate)/(1000*60*60*24);
        DayCount=Math.round(DayCount); 
    return(DayCount);
}

Update: Still playing around with it...
However, I'm unable to have a user enter the date in one input box and have it output the number of days between that input date and the end of the year... How do I make that display happen. It's just not working for me. I have the display field set as "hidden but printable"...does that make any difference?