Help modifing an existing script...

[DBookatay]

I found (ok ok, stole) a finance calculator script from MSN Auto http://autos.msn.com/loancalc/newloan.aspx, (Bill Gates stole from everyone else, it's just a little payback...) and need to add new fields to it to use form my application. Can someone please help?

 

I want to add:

      Additional months: 30 and 54, but the script will not allow it

      Sales tax: 1 of 4 percentages: 6.000%, 7.375%, 8.125% or 8.375% (which the user would select based by an <select name="calcTax"></select>)

      Registration: 1 of 6 choices: $45, $60, $85, $120, $160, $210 (again controlled by <select name="calcReg"></select>)

 

Can someone with java experience please help me with this, it would be greately apprechiated...

[DBookatay]

Can someone please help?

 

I completely forgot to include the code:

<script language="javascript">

var g_fRateStep = 0.05; // The smallest amount the interest rate can be modified by
var g_nRateMultiple = 120;
var g_nTermMultiple = 5;
var g_strMonthly = 0; // Used by UpdateTotalCost (so that we don't need to interrogate the UI when the Monthly Payment is the target value)
var g_fPurchasePrice = 0;


// Install event handlers...
window.onload = OnFormLoad;


function OnFormLoad(event)
    {
    UpdateTargetValue();
    document.LoanCalcForm.elements[2].focus();
    }


function OnResize(event)
    {
    document.location.reload(false);
    }


function UpdateTargetValue()
    {
    
	UpdateMonthly();

    }


function FormatCurrency(strValue)
    {
    var strDecimalSeparator = '.';
    var strThousandSeparator = ',';
    var nPos = strValue.indexOf('.');
    var nLen = parseInt(strValue, 10).toString().length;

    if (nPos > 0)
        strValue = strValue.substr(0, nPos) + strDecimalSeparator + strValue.substr(nPos + 1, strValue.length - nPos);
    else
        nPos = strValue.length;

    while (nLen > 3)
        {
        nPos -= 3;
        strValue = strValue.substr(0, nPos) + strThousandSeparator + strValue.substr(nPos, strValue.length - nPos + 1);
        nLen -= 3;
        }

    return '$' + strValue;
    }


function ChangeCalcType(strType)
    {
    var strExtra;
    
    if (strType == 'monthly')
        {
        
        return;
        
        strExtra = '&price=' + g_fPurchasePrice.toString();
        }
    else
        {
        
        strExtra = '&pmt=' + (Math.round(g_strMonthly)).toString();
        }
        
    location.href='/loancalc/newloan.aspx?calc=' + strType + '&dp=' + (document.LoanCalcForm.elements[2].value).toString() + '&trm=' + g_nTermMultiple.toString() + '&int=' + g_nRateMultiple.toString() + strExtra;   
    }


function UpdateTotalCost()
    {
    var nDownPayment = isNaN(parseInt(document.LoanCalcForm.elements[2].value, 10)) ? 0 : parseInt(document.LoanCalcForm.elements[2].value, 10);
    var nTerm = g_nTermMultiple * 12;
    
	var fMonthlyPayment = parseFloat(g_strMonthly);
    
    var fTotalCost = parseFloat(parseInt(nDownPayment, 10) + (fMonthlyPayment * nTerm));

    fTotalCost = Math.round(fTotalCost);

    
	document.all.TotalCost.innerHTML = '<span class="bignum"><nobr>' + FormatCurrency(fTotalCost.toString()) + '</nobr></span>';
    
    }


function UpdatePrice()
    {
    var fRate = g_nRateMultiple * g_fRateStep;
    var nTerm = g_nTermMultiple * 12;
    var nDownPayment = isNaN(parseInt(document.LoanCalcForm.elements[2].value, 10)) ? 0 : parseInt(document.LoanCalcForm.elements[2].value, 10);
    var nPayment = isNaN(parseInt(document.LoanCalcForm.elements[3].value, 10)) ? 0 : parseInt(document.LoanCalcForm.elements[3].value, 10);
    var fMonthlyRate = (fRate * 0.01) / 12.0;
    var fPower = Math.pow(1.0 + fMonthlyRate, -nTerm);
    var fPrice = parseInt((fMonthlyRate == 0 ? ((nPayment * nTerm) + nDownPayment) :
                                                ((nPayment * ((1.0 - fPower) / fMonthlyRate)) + nDownPayment)), 10);

    
    g_fPurchasePrice = fPrice;

    
	document.all.Price.innerHTML = '<span class="bignum"><nobr>' + FormatCurrency(parseInt(fPrice, 10).toString()) + '</nobr></span>';
    
    UpdateTotalCost();
    }


function UpdateMonthly()
{
    var fRate = g_nRateMultiple * g_fRateStep;
    var nTerm = g_nTermMultiple * 12;
    var nDownPayment = isNaN(parseInt(document.LoanCalcForm.elements[2].value, 10)) ? 0 : parseInt(document.LoanCalcForm.elements[2].value, 10);
    var nPrice = isNaN(parseInt(document.LoanCalcForm.elements[3].value, 10)) ? 0 : parseInt(document.LoanCalcForm.elements[3].value, 10);

    if (nDownPayment > nPrice) nDownPayment = nPrice;
    
    var fMonthlyRate = (fRate * 0.01) / 12.0;
    var fPower = Math.pow(1.0 + fMonthlyRate, -nTerm);
    var fMonthly = (fPower == 1.0 ? (nPrice - nDownPayment) / nTerm :
					            (nPrice - nDownPayment) * (fMonthlyRate / (1.0 - fPower))) ;

    if(fMonthly.toString().substr(0, 1) == '.')
        fMonthly = '0' + fMonthly.toString();

    
	g_strMonthly = parseInt(fMonthly, 10).toString() + (Math.round((fMonthly - parseInt(fMonthly, 10)) * 100) / 100).toString().substr(1, 3);
	if ((g_strMonthly.toString().indexOf('.', 0) > 0) && (g_strMonthly.toString().length - g_strMonthly.toString().indexOf('.', 0) == 2))
		g_strMonthly = g_strMonthly.toString() + '0';
	document.all.Monthly.innerHTML = '<span class="bignum"><nobr>' + FormatCurrency(g_strMonthly) + '</nobr></span>';
    

    UpdateTotalCost();
    }


function UpdateRate(bDoUpdate)
    {
    with (document.LoanCalcForm.elements[4])
        {
        var fTemp = options[selectedIndex].value / 0.05;
        
        g_nRateMultiple = fTemp;
        if (g_nRateMultiple - parseInt(fTemp) > 0) 
            g_nRateMultiple = parseInt(g_nRateMultiple) + 1;
        }
    if (bDoUpdate)
        UpdateTargetValue();
    }


function UpdateTerm(bDoUpdate)
    {
    with (document.LoanCalcForm.elements[5])
        {
        var fTemp = options[selectedIndex].value / 12;

        g_nTermMultiple = fTemp;
        if (g_nTermMultiple - parseInt(fTemp) > 0) 
            g_nTermMultiple = parseInt(g_nTermMultiple) + 1;
        }
    if (bDoUpdate)
        UpdateTargetValue();
    }


function ValidKey(nKeyCode, bShift, bCTRL)
    {
    if (nKeyCode != 37 &&                  // Left cursor
        nKeyCode != 39 &&                  // Right cursor
        nKeyCode != 8  &&                  // Backspace
        nKeyCode != 9  &&                  // Tab
	nKeyCode != 46 &&                  // Delete
        nKeyCode != 16 &&                  // Shift
        nKeyCode != 35 &&                  // End
        nKeyCode != 36 &&                  // Home
        (nKeyCode < 48 || nKeyCode > 57))  // 0 - 9
        return false;
    else
        return true;
    }


function Validate()
    {
	var nKeyCode = window.event.keyCode;
	var bShift = window.event.shiftKey;
	var bCTRL = window.event.ctrlKey;
    

    if (!ValidKey(nKeyCode, bShift, bCTRL))
        return false;
    else
        return true; 
    }


function UpdateDownPayment()
    {
    
    var nDownPayment = isNaN(parseInt(document.LoanCalcForm.elements[2].value, 10)) ? 0 : parseInt(document.LoanCalcForm.elements[2].value, 10);
    var nPurchasePrice = parseInt(document.LoanCalcForm.elements[3].value, 10);

    UpdateMonthly();
    
    }


function Update()
    {
    
    var nDownPayment = parseInt(document.LoanCalcForm.elements[2].value, 10);
    var nPurchasePrice = parseInt(document.LoanCalcForm.elements[3].value, 10);
    
    UpdateMonthly();
    
    }

</script>

 

 

[DBookatay]

Anyone?