function update() {
  if (request.readyState == 4) {
    if (request.status == 200) {
      /* Get the response from the server */
      var response = request.responseText;
      var array = response.split("|");
      var alertNumber = array[0];
      var alertText = array[1];
      if (alertNumber == "1") {
      window.location = alertText;
      } else if (alertNumber == "2") {
      alert(alertText);
      document.getElementById("continue").disabled=false;
      } else {
      var required = array[2].split("~");
      for (i=0; i < required.length; i++) {
      var name = required[i]+"_label";
      document.getElementById(name).className="label_red";
      }
      document.getElementById("alert").innerHTML=alertText;
      document.getElementById("continue").disabled=false;
      }
     } else {
      alert("Error! Request status is " + request.status);
    }
  }
}

function process() {
   document.getElementById("alert").innerHTML="<span class=\"label_green\">Working...Please wait.</span>";
   document.getElementById("continue").disabled=true;
   var label_string = "amount";
   var labels = label_string.split("~");
   for (i=0; i < labels.length; i++) {
      var name = labels[i]+"_label";
      document.getElementById(name).className="label";
   }
   var amount = document.getElementById("amount").value;
   var recurring_billing = document.getElementById("recurring_billing").value;
   var url = "donate_do.php";
   request.open("POST", url, true);
   request.onreadystatechange = update;
   request.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
   request.send("amount=" + escape(amount) + "&recurring_billing=" + escape(recurring_billing));       
}