How do I set up this calculation?

Question

Hello everyone, this is my first post, and I'm happy to become part of the Acrobat community!
So I have been trying to create a form, and I mostly got it all figured out, except for this bit of calculation that I simply can't get to work.
This is for a purchase proposal, and I need to have it so that clients only need to fill some fields, and others are automatically calculated. There are 4 fields, let's call them Field A, Field B, Field C and Field D. In Field A, which is for currency, the client will type the proposal value, and in Field B he will type the percentage of the value in Field A that he will pay in advance. Field C is set to automatically figure how much, in currency, he will have to pay from the calculation between Field A and Field B. For example, if the client sets 100000$ in Field A and 10% in Field B, Field C will automatically say that the value to pay in currency is 10000$. Now, this was not that hard. I looked around and found a Java Script that does just that.
Now, Field D is supposed to tell the client how much, in currency, he will pay in the final contract, after he has already payed the 10% advance. So, in other words, Field D should be Field A minus Field C. So the question is, what Script do I need to make this calculation automatically after the client types in the values of Field A and Field C?
I hope I was able to explain it properly.
Thank you so much!

Answer 1

Where is the script located?
What is not working about this script?
Have you looked at the JavaScript console for errors?
Try the following script in Field D:
function GetField(cName) {
var oField = this.getField(cName);
if(oField == null) app.alert("Error accessing field named " + cName, 1, 0);
return oField;
} // end GetField funciton;
// custom calculation for Field D;
// define some feild names;
var cTotalPayment = "Field A"; // total payment due;
var nPercentDown = "Field B"; // percentage down (assumes non-decimal value);
var nDownPayment = "Field C"; // downpayment amount;
// end of field names
// some debugging help;
console.show();
console.clear();
console.println("Total Payment: " + GetField(cTotalPayment).value);
console.println("Percent for downpayment: " + GetField(nPercentDown).value);
console.println("Downpayment amount: " + (GetField(cTotalPayment).value * (GetField(nPercentDown).value / 100)));
console.println("Balance due: " + (GetField(cTotalPayment).value - (GetField(cTotalPayment).value * (GetField(nPercentDown).value / 100))));
// end debugging help;
// compute the downpayment amount;
GetField(nDownPayment).value = GetField(cTotalPayment).value * (GetField(nPercentDown).value / 100);
// compute balnance due;
event.value = GetField(cTotalPayment).value - GetField(nDownPayment).value;