Javascript subtract times

IanD posted this at 22:42 — 16th April 2007.

Joined: Sep 1999

I'm modifying a timesheet application and have users enter times in hour:minutes format and select am/pm from a dropdown. I want to be able to subtract the ending time from the start time to get the # of hours worked on a project. It sounds like it'd be pretty simple, but I'm having a lot of trouble with it.

Here's my latest attempt.

function calculateHours()
		{
			var startTime	= document.getElementById("<%=startTime.ClientID%>");
			var endTime		= document.getElementById("<%=endTime.ClientID%>");
			
			
			if(startTime.value != '' && endTime.value != '')
			{
				var startPeriod	= document.getElementById("<%=startPeriod.ClientID%>").value;	
				var endPeriod	= document.getElementById("<%=endPeriod.ClientID%>").value;
				var hoursOutput	= document.getElementById("<%=Hours.ClientID%>");
				startTime 		= startTime.value.split(":");
				var startHour		= parseInt(startTime[0]);
				var startMinutes	= parseInt(startTime[1]);
				endTime				= endTime.value.split(":");
				var endHour			= parseInt(endTime[0]);
				var endMinutes		= parseInt(endTime[1]);
				var hours, minutes;
				
				// Convert to 24 hour time to do calculation
				if(startPeriod == "pm" && startHour != 12)
					startHour += 12;
				if(endPeriod == "pm" && endHour != 12)
					endHour += 12;
				
			
				var time1, time2, time3, today;
				today = new Date();
				time1 = new Date(today.getFullYear(), today.getMonth(), today.getDay(), startHour, startMinutes, 0);
				time2 = new Date(today.getFullYear(), today.getMonth(), today.getDay(), endHour, endMinutes, 0);
				time3 = new Date();
				time3.setTime(time2.getTime() - time1.getTime());
				
				//alert(startHour + " " + startMinutes + " " + endHour + " " + endMinutes + " " + time1.getTime() + " " + time2.getTime() + time3.getHours);
				alert(time3.getTime);
			}
		}

Basically, it's converting both times to the # of milliseconds since the unix epoch and then subtracting them to get the difference, then setting that as the time on a 3rd object. But when I echo getTime it just shows the function decleration.

Fighting for a Lost Cause.net

Abhishek Reddy posted this at 18:48 — 17th April 2007.

He has: 3,348 posts

Joined: Jul 2001

Your alert call should probably be [incode]alert(time3.getTime())[/incode]. As it is, [incode]time3.getTime[/incode] only refers to the function object, rather than calling it.