How to hide and show some field on a radio button click

This is my code part:-

PAYMENT DETAILS

 <table cellpadding="0" cellspacing="0" align="center" border="5" bordercolor="#003333" align="center" width="70%">
     <tr>
       <td width="25%">
          <b class="label">Payment Type<b>
       </td>
       <td width="40%">
        <INPUT TYPE=radio NAME="payment_method" VALUE="cash" CHECKED><b class="label">By Cash</b></input>
         <INPUT TYPE=radio NAME="payment_method" VALUE="cheque" onclick="return payment();"><b class="label">By Cheque</b></input>
       </td>  
       <td>
          <b class="label">Payment Date<b>
       </td>
       <td>
      <jsp:include page="calendar_1.html" />


       </td>       
     </tr>
     <tr rowspan="4">
       <td>
          <b class="label">Cheque Number<b>
       </td>
       <td>
            <input type="text" value="" name="chqno">
       </td> 
        <td>
          <b class="label">Bank Name<b>
       </td>
       <td>
            <input type="text" value="" name="bankname">
       </td>  
     </tr>
     <tr colspan="2">

       <td>
          <b class="label">Amount<b>
       </td>
       <td>
            <input type="text" value="" name="amount1">
       </td>       
     </tr>
 </table>

I want bank name and cheque number label and textbox to be invisible when by cash radio button is clicked.and they should be visible when by cheque radio button is clicked.

I have applied javascript for this as:-

function payment(e) { if (e.value==cash) { document.getElementById(chqno).style.display=block; document.getElementById(bankname).style.display=block; } else { document.getElementById(chqno).style.display=none; document.getElementById(bankname).style.display=none; }

}

please help me with this