please guy help me. i have just already learn about javasciprt. and i have this source code

<!--FINANCE CALCULATOR START-->
<script language="javaScript" type="text/javascript">
<!--
function showpay() {
if ((document.calc.loan.value == null || document.calc.loan.value.length == 0) ||
(document.calc.months.value == null || document.calc.months.value.length == 0)
||
(document.calc.rate.value == null || document.calc.rate.value.length == 0))
{ document.calc.pay.value = "Incomplete data";
}
else
{
var amt = parseFloat(document.calc.loan.value);
var month = parseFloat(document.calc.months.value);
var intr = parseFloat(document.calc.rate.value);
var nilai1 = intr/100/12;
var nilai2 = (1+nilai1);
var nilaix = Math.pow(nilai2,-month);
var nilai3 = 1-nilaix;
var final = amt*(nilai1/nilai3);

document.getElementById("total").innerHTML = "Angsuran/bulan : <strong>"+final.toFixed(2)+"</strong>";
}

// payment = principle * monthly interest/(1 - (1/(1+MonthlyInterest)*Months))

}

// -->
</script>
<form name="calc" method="post" action="">
<h3><?php _e($title); ?> </h3>

<div class="form_row clearfix">
<label> <?php _e('Pinjaman');?> : </label> <input type="text" name="loan" class="textfield" />
</div>
<div class="form_row clearfix">
<label><?php _e('Jmh Bln');?> : </label>
<input type="text" name="months" class="textfield" />
</div>
<div class="form_row clearfix" >
<label> <?php _e('Bunga');?> (%): </label> <input type="text" name="rate" class="textfield" />
</div>
<div class="form_row clearfix" >
<p id="total"> </p>
</div>
<input type="button" onclick="showpay()" value="<?php _e('Hitung');?>" class="btn_input_highlight" />
</form>

The question is i want to change the format of user input for example , user put 10000000 automaticly change to 10.000.000. but when processed to calculation script its still number as 10000000