Confirm Box for Saving a Customer Record

I have a scripting question about getting user feedback before executing a certain block of code.

function...
  if(customerRef != null && customerRef != "")
  {
   //return confirm("This will deduct an issue from the customer.  Click OK to deduct an issue or Cancel to save the record without deducting an issue.");

Basically what happens is if a certain checkbox is checked on the customer record (which will deduct an issue from the customer's prepaid issues remaining), it runs this part of the code when the user saves the record.  But I want to ask the user if they really want to perform this action.  If they click "yes" or "ok", go ahead and perform the rest of the code.  If they click "no" or "cancel", abort the script and the saving process so they can go back and uncheck the checkbox.  With the "return confirm" function, clicking 'OK' saves the record,