function validateFields(frm) {
    
    frm.price.value =cleandollaramounts(frm.price.value)
    frm.downPmt.value = cleandollaramounts(frm.downPmt.value);
    frm.interest.value=cleanInterestRate(frm.interest.value);
    
    if (isNaN(frm.price.value)) {
      alert ('Please use numbers only in the Price field.');
      return false;
    }
    if (isNaN(frm.downPmt.value)) {
      alert ('Please use only numbers in the Down Payment field.');
      return false;
    }
    if (isNaN(frm.interest.value)) {
      alert ('Please use only numbers in the Interest Rate field.');
      return false;
    }
    if (frm.interest.value.length == 0) {
      alert ('You must enter an interest rate');
      return false;
    }
    
    return true;
    
  }
  
  
  function calcPayment (frm) {
    
    if(!validateFields(frm)) {
      return false;
    }
    var total = (frm.price.value - frm.downPmt.value);
    var rate = (frm.interest.value / 100) /12;
    if (rate == 0) {
      var monthlytotal = total / frm.length.value;
    } else {
      var monthlytotal = total * rate / (1 - (Math.pow(1 / (rate+1), frm.length.value)));
    }
    frm.calcpmt.value = dollarFormat(monthlytotal);
  }
  
  
  function dollarFormat(number) {
    
    neg=false;
    
    if(number < 0) {
      neg=true;
    }
    number = Math.abs((Math.round(number * 100) / 100));
    number = "" + number;
    if (number.indexOf(".") == -1) {
      number += ".00";
    }
    beforedot = number.substr(0, number.indexOf("."));
    afterdot = number.substr(number.indexOf("."));
    while (afterdot.length < 3) {
      afterdot += "0";
    }
    if (beforedot >= 10000) {
      lengthofbeforedot=beforedot.length;
      beforedot = parseInt("" + (beforedot / 1000)) + "," + beforedot.substring(lengthofbeforedot - 3, lengthofbeforedot);
    }
    ret = beforedot + afterdot;
    if(neg) {
      ret = '(' + ret + ')';
    }
    
    return "$"+ret;
    
  }
  
  
  function cleandollaramounts(amt) {
    
    amt = replaceAll( amt, ",", "" );
    
    return replaceAll( amt, "$", "" );
    
  }
  
  
  function cleanInterestRate(rate) {
    
    rate2 = replaceAll( rate, "%", "" );
    
    return rate2;
    
  }
  
  
  function replaceAll( str, from, to ) {
    
    var index = str.indexOf( from );
    while ( index > -1 ) {
      str = str.replace( from, to );
      index = str.indexOf( from );
    }
    
    return str;
    
  }

  function hideCalculator() {
    
    document.getElementById('PaymentCalculator').style.display='none';
    
  }