Accessing Form Array Elements

[tonybui]

I am very new to javascript. I have a problem getting to any element from this form generated by the jsp page using struts. Please show me how to get to item[0].totalAmount for example, so that I can create a function to calculate the calculateTotal(). So far, when I do the alert, it is only valid up to
document.myForm.item; the document.myForm.item[0] is invalid according to the alert. Any help is very much appreciated.

function calculateTotal(){
   alert(document.myForm.item);
}
<form name="myForm" method="post" action="/myAction.do">
  <table id="display" border="1">
     <tr>
     	<th scope="col" id="totalAmount">Total Amount</th>
     	<th scope="col" id="adjustmentAmount>Adjustment Amount</th>
     	<th scope="col" id="newAmount">NewAmount</th>
     </tr>
     <tr>
        <td><input type="text" name="item[0].totalAmount" id="totalAmount"  value="100" readonly="readonly"></td>
        <td><input type="text" name="item[0].adjustmentAmount" id="adjustmentAmount" 
                   value="" onblur="javascript:calculateTotal();" readonly="readonly"></td>
     	<td><input type="text" name="item[0].newAmount" id="newAmount" value="" readonly="readonly"></td>   
     </tr>
     <tr>
        <td><input type="text" name="item[1].totalAmount" id="totalAmount" value="350" readonly="readonly"></td>
        <td><input type="text" name="item[1].adjustmentAmount" id="adjustmentAmount" 
                        value="" onblur="javascript:calculateTotal();" readonly="readonly"></td>
     	<td><input type="text" name="item[1].newAmount" id="newAmount" value="" readonly="readonly"></td>   
     </tr>
  </table>
 </form>