javascript calculator in php loop

[modcar]

Evening;

 

I am creating a 5 part registration form, with sets of fields dynamically created, depending on the options a user has previously selected.

 

Step 4 is where I'm having issues, I cannot get the form calculator working.  I have tried having the javascript in the loop, and out, but no difference.

 

code for calculator:

<script type="text/javascript">
function startCalc2(){
  interval = setInterval("calc2()",1);
}
function calc2(){
  
   
   one_lic_total = document.autoSumForm.car1_lic_quote.value;
   two_lic_total = document.autoSumForm.car2_lic_quote.value;
   document.autoSumForm.reg_quote.value = ((one_lic_total * 1) + (two_lic_total * 1)).toFixed(2);
  
    total_lic = document.autoSumForm.lic_quote.value;
   total_admin = document.autoSumForm.admin_fee_quoted1.value;
  document.autoSumForm.quote_total.value = ((total_lic * 1) + (total_admin * 1)).toFixed(2);
  
  calc_car1_lic = document.autoSumForm.car1_lic_12_6.value;
  document.autoSumForm.car1_lic_quote.value = (calc_car1_lic * 1)
  
  calc_car2_lic = document.autoSumForm.car2_lic_12_6.value;
  document.autoSumForm.car2_lic_quote.value = (calc_car2_lic * 1)
  }
function stopCalc2(){
  clearInterval(interval);
}
</script>

 

This worked when there was only 1 or 2 cars, but, now that there could be any number of cars

 

The feilds still follow the same naming as above,

<select name="car<? echo $num; ?>_lic_12_6" id="car<? echo $num; ?>_lic_12_6" onChange="startCalc2()">