Calculate Difference (minus) for Form Fields

Have you read the answer to [url=http://www.acrobatusers.com/forums/aucbb/viewtopic.php?id=15754]Calculate Difference (Minus) in Form Field[/url]?

Yes, I read that reply posting. In truth I found it unelucidating, although I definitely appreciate your time and attention. How do i write a custom script? How do i use simplified field notation? How do i know if my field names comply with simple name format? Lastly, what is eSeminar? Thank you!

Alex Adams

The eSeminar on demand is about Acrobat forms. Then there is the How To JavaScript Corner article about Acrobat Froms Custom calculation scripts.

So for the field for the difference:

Simplified field notation:
FieldAName - FieldBName
Custom calculation script:
event.value = this.getField("FieldAName ").value - thie.getField("FieldBName").value;

Thank you SO MUCH! You are a real life saver. I have been pulling out my hair about this for days.

Cheers,
Alex Adams

I need to calculate the total time spent on site at a customers locations
I have a field "Start Time" and a field "Stop Time"
I would like to have the field "Total Time" calculated in Total Hours
I can not figure out the the correct Code

is this on the right track:
var c = this.getField("Stop Time").value;
var d = this.getField("Start Time").value;
event.value = c - d;

I have the Time Fields set to HH:MM (24 Hour Clock)

Date and Time fields have a formatted value, you need to convert these formatted strings to JavaScript date time object, then extract the number of days from the epoch date, and then do the math.

Have you read Thom Parker's JavaScript tutorials about working with date and time in JavaScript?

Yes I have but I am still a little confused
But I understand I need to Convert
"Start Time" field to Decimal
"Stop Time" field to Decimal
Then Calculate the Difference, Convert the "Difference" back to Hours and Minutes.

A quick search turns up [url=http://www.acrobatusers.com/forums/aucbb/viewtopic.php?id=22148]Calculating difference between date and time[/url].

The 'util.scand()' method converts the date time string to the date object.

The '.getTime()' method gets the number of milliseconds from the epoch date, or you use the 'valueOf()' method will also get the number of milliseconds from the epoch date.

You can then either convert the milliseconds minutes and calculate the difference or use milliseconds for the difference computation and then convert the difference to minutes.

You then need to use the 'round()' method of the 'Math' object to obtain the value of the minutes from the difference. You can then use the modulus, '%', operator to get the minutes minutes remainder from dividing by 60 minutes to the hour. Then use the 'Math.floor()' method to get the hours and days from the difference in minutes. You can then use these values to create a formatted string.