Excel PMT function in JS

I found i little snipet on internet, about PMT calculate.

function PMT(i, n, p) {
 return i * p * Math.pow((1 + i), n) / (1 - Math.pow((1 + i), n));
}
function CalculatePMTFromForm(idLoanAmount, idAnnualInterestRate, idMonths, idResult) {
 var i = jQuery('#' + idAnnualInterestRate).val() / 1200;
 var n = jQuery('#' + idMonths).val();
 var p = jQuery('#' + idLoanAmount).val();
 var pmt = PMT(i, n, -p);
jQuery('#' + idResult).val(pmt.toFixed(2));
}
function performCalc() {
 CalculatePMTFromForm('LoanAmount', 'InterestRate', 'Months', 'Payment');
}
jQuery(document).ready(function() { performCalc(); jQuery('.calc').keyup(performCalc); });

When the page is load, in the result input box I see "NaN" , and when i tpye some irrelevant number then "-Infinity" msg appear. I search to "NaN" in files and i found in jquery.js, but after I modify, nothing change. And I can't find Infinity

How can I change this messages?

Edit

Calling code:-

function performCalc() {
  CalculatePMTFromForm('LoanAmount', 'InterestRate', 'Months', 'Payment');
}

jQuery(document).ready(function() {
  performCalc(); jQuery('.calc').keyup(performCalc);
});

This is worked for me:

if(pmt>0 && pmt<Number.MAX_VALUE) {jQuery('#' + idResult).val(pmt.toFixed(2));}