I have a somewhat complicated fee calculation that I woudl like to do with javascript. I need to pass this calculated value to Paypal as the amount. I understand that I cannot use javascript in the Calc_TotalField area. Using a client side event to modify a hidden field doesn't seem to work.
I have been successful at using client side events to calculate the value of a text box and pass that to Paypal. However, if I make the text box read-only, the amount does not get passed to Paypal. I can't let people change the amount that they will be charged.
What is the best way to accomplish this?