help w/onblur

[88f615f6]

I'm trying to use js function to: upon entering "paidamt" change the "amtdue",
"prevbal",auto-insert the current date(datepaid), change"pd", and increment
the "checkno". I had this working at one time but memory precludes the use of the
onblur. The following code displays all values for selected record from database
and only updates "paidamt". Any help?
 

echo "<tr>
<td><input type='text' readonly size=15 name='acctno' value='" . $row['acctno'] . "' ></td>
<td><input type='text' readonly size=25 name='bname' value='" . $row['bname'] . "'></td>
<td><input type='text' readonly size=25 name='purpose' value='" . $row['purpose'] . "'></td>
<td><input type='text' size=7 id='paidamt' name='paidamt' value='" . $row['paidamt'] ."'
onBlur='calculate_paid(this)'></td>
<td><input type='text' size=5 name='amtdue' value='" . $row['amtdue'] . "' ></td>
<td><input type='text' size=5 name='prevbal' value='" . $row['prevbal'] . "' ></td>
<td><input type='text' size=5 name='datepaid' value='" . $row['datepaid'] . "' ></td>
<td><input type='text' size=5 name='pd' value='" . $row['pd'] . "' ></td>
<td><input type='text' size=5 name='checkno' value='" . $row['checkno'] . "' ></td>
</tr>";

function $_(IDS) { return document.getElementById(IDS); }
function calculate_paid()
  {
   var recur = parseInt(document.getElementById("recur").value;
   var pd = parseInt(document.getElementById("pd").value;   
   var shipamt = parseFloat(document.getElementById("shipamt").value;
   var paidamt = parseFloat(document.getElementById("paidamt").value;
   var prevbal = parseFloat(document.getElementById("prevbal").value;
   var amtdue = parseFloat(document.getElementById("amtdue").value;
   var checkno = parseInt(document.getElementById("checkno").value;
   var datepaid = parseFloat(document.getElementById("datepaid").value;
   var dateNow = new Date();
   var dayNow = dateNow.getDate();
   var datePaid = (dateNow.getMonth()+1)+"/"+dateNow.getDate()+"/"+dateNow.getFullYear();
      datepaid.value = datePaid;
prevbal.value = parseFloat(amtdue.value) + parseFloat(shipamt.value) - parseFloat(paidamt.value);
amtdue.value = parseFloat(amtdue.value) + parseFloat(shipamt.value) - parseFloat(paidamt.value);
checkno.value = parseInt(checkno.value) + "1";
   if(recur.value=="N")
      {prevbal.value= amtdue.value;}
   if(prevbal.value=="0.00")
      {pd="P";}
   if(amtdue.value=="0.00")
      {pd="P";}