How to Subtract and Add in Form Fields

JavaScript uses the "+" operator for arithmetic addition and string concatenation and also is not very strict about enforcing field types like string and numeric. The result is that JavaScript tries to guess what the field type is based on the value and the operator. But in many cases gets this wrong so for your string of "+" operations you may have the first 2 fields added because they are non-blank numbers but since th3 3rd field is blank it is treated as a string and the 3rd and following fields are concatenated. So you need to force JavaScript to use a numeric value and not a string value. This can be done by using the 'Number()' constrictor or multiplying each value by 1.


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Thank you SO much! It works perfectly now! I can't thank you enough... I GREATLY appreciate your help! :) -dave

thank you ... this also helped me w/ getting rid a a whole bunch of hidden fields a previous person left on a form I need

THANKS!

I would appreciate some help. I have read all the submissions and so must be doing something wrong, but do not know what. I have three fields - SubTotal, DisAmount and TotalDue. SubTotal and DisAmount are both calculated fields and then TotalDue = SubTotal-DisAmount. I have checked the order and it is correct.

I have tried the simplified code of SubTotal-DisAmount and also more complicated scrips of:
var a = this.getField("SubTotal).value;
var b = this.getField("DisAmount).value;
event.value = a-b;

as well as
var a = this.getField("SubTotal);
var b = this.getField("DisAmount);
event.value = a.value -b .value;

I also tried

event.value = Number(this.getField("SubTotal").value) - Number(this.getField(DisAmount).value);

However, all that happens is that the value in the field doesn't change. If I change one of the other fields, everything calculates correctly except TotalDue which remains fixed. There are no errors that I can find.

I have tried a number of the submissions but none work so I don't know what I am doing wrong, but would appreciate some direction.

Thanks

In the both code snippets, you did not enter the trailing quotation mark needed to terminate the character string for the field name character stings.


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If you look at Acrobat's JavaScript debugging console, the message "un terminated string literal" indicates JavaScript does not know where a character string ends and the JavaScript code continues.

gkaiseril, your post is very informative and is exactly what I have been looking for; however, it isn't working for me and I hope you can help.
I have created a form intended to calculate net worth. I have one column for assets, and another for liabilities. Each of these two columns, respectively, has a totals field. To calculate the net worth field, I need to subtract total liabilities from total assets. When I write the formula into the simplified field notation, which is ValueTOTAL ASSETS - TOTAL LIABILITIES, nothing happens. It does not calculate.
Do you have any ideas?

You can not easily use '.' or spaces in field names in the Simplified Field notation. You need a special leading character called the 'Escape' character in JavaScript. If you use the '.' or a space in a field name, you need to precede that character with the "\" character. So the entry for the Simplified Field Notation should be:

TOTAL\ ASSETS - TOTAL\ LIABILITIES

The field still isn't populating. I'm not doing something correctly, but don't know what.

I figured it out. You were extremely helpful. Thanks so much for your help, George.