function processForm() {
 var value = 0;
 
  if (document.getElementById("radiocost1").checked) {
    document.getElementById("cost1").value = 10;
  } else if (document.getElementById("radiocost2").checked) {
    document.getElementById("cost1").value = 25;
  } else if (document.getElementById("radiocost3").checked) {
    document.getElementById("cost1").value = 50;
  } else if (document.getElementById("radiocost4").checked) {
    document.getElementById("cost1").value = 100;
  } else { 
    value = parseFloat(document.getElementById("cost1").value);
    if (value == "NaN") {
      document.getElementById("cost1").value = 10;
    }
  }
  
  alert("cost: " + document.getElementById("cost1").value);
  
  document.formDonation.submit();
}