function <% $opt{prefix} %>invoice_select_changed(what) {
var surcharge;
+ var invdue = document.getElementById("<% $opt{prefix} %>inv" + what.value);
if (document.getElementById('surcharge_percentage') || document.getElementById('surcharge_flatfee')) {
- surcharge = (+what.value * +document.getElementById('surcharge_percentage').value) + +document.getElementById('surcharge_flatfee').value;
+ surcharge = (+invdue.value * +document.getElementById('surcharge_percentage').value) + +document.getElementById('surcharge_flatfee').value;
}
else { surcharge = 0; }
- var amount = +what.value + +surcharge;
+ var amount = +invdue.value + +surcharge;
if ( what.value == 'select' ) {
$('#payment_amount_row').hide();