Javascript for making form fields multiply & add up

Hi!

I've created a form using html and asp that is an order form that is emailed.

I am looking to insert formulas into the text areas of the form- similar to an excel sheet... Basically the form should look like this...

Part Number Description Quantity Cost Amount
74897389 First Item 4 $5 $20
43274387 Second Item 2 $6 $12
Total: $32

So basically I need two types of formulas... One that will multiple the quantity and the cost- and put that number in the "amount" cell for that product. The other formula will add up the last row (all of the amounts) and put that final figure in a "total" field.

Then once these fields are automatically filled in, and the user has completely the form, the Submit button will include these calculations in the email as well.

I use 3dcart which does not support PHP.

I've done a lot of searches for this, but I'm not finding the answer!

Any help would be MUCH appreciated!!!

 

Is this a stupid question? Because a lot of people have viewed it but not responded... Even just some hints would great!

 

I don't realy understand your question. But this is what I would do for javascript.

put this in an onchange function on each of the fields

javascript:

//gets values of field 1 and 2
f1 = document.getElementById('field1').value;
q1 = document.getElementById('quantity1').value;
f2 = document.getElementById('field1').value;
q2 = document.getElementById('quantity2').value;
if(f1 != null && f2 != null)
{
//does math on the values of field 1 and 2
  f1 = f1*q1;
  f2 = f2*q2;
  od = f1 + f2;
//makes the value of outputfield = field1 + field2
  document.getElementById('outputfield').value = od;
}

Code (markup):

I'm not sure if this is what you want. If it isn't please explain your question better.

 

Can anybody explain how to calculate total amount in html form?

I want to calculate and process while the visitor clicks check out. And the calculation is like to multiply and add to the amount.

For eg., a visitor has enter amount as 10 and I need to multiply it with 25 and add 20% to the value and which click checkout, it should be 300. So how can I get that in a html form?