Math Related : Credit Card Debt Calculator

Chris Crenshaw May 30, 2008

General

This script will calculate how long it will take to pay off credit card debt. It will also calculate the total interest that will be paid over that same period.

Notes

Created by: Chris Crenshaw
Web Site: http://www.creditcarddebtnegotiation.org/

Source Code

Paste this source code into the designated areas.

External file

Paste this code into an external JavaScript file named: creditCardDebtCalculator.js

/* This script and many more are available free online at
The JavaScript Source!! http://www.javascriptsource.com
Created by: Chris Crenshaw | http://www.creditcarddebtnegotiation.org/ */

// validation function
function isValid(entry, a, b) {
  if (isNaN(entry.value) || (entry.value==null) || (entry.value=="") || (entry.value < a) || (entry.value > b)) {
  alert("Invalid entry. Your min payment should be between " + a + " and " + b + ".")
	entry.focus()
  entry.select()
	return false
  }
	return true
}

// clear results fields when input values changed
function clearCalcs(form) {
	form.num_months.value = ""
	form.total_pay.value = ""
	form.total_int.value = ""
}

function calculate(form) {
// send entries to validation function
// exit if not valid
	if (!isValid(form.balance, 0, 100000)) {  
		return false
	} else if (!isValid(form.interest, 0, 30)) {  
		return false
	} else {         
		var init_bal = eval(form.balance.value);
	}
	if (!isValid(form.mnth_pay, init_bal*.02, init_bal)) {
		return false
  } else {
	// variables used in calculation
	var cur_bal = init_bal;		// used in loop
	var interest = eval(form.interest.value/100);
	var mnth_pay = eval(form.mnth_pay.value);
	var fin_chg = 0;			// finance charge
	var num_mnths = 0;
	var tot_int = 0;
  }
	
  while (cur_bal > 0) {
    fin_chg = cur_bal*interest/12;
    cur_bal = cur_bal - mnth_pay + fin_chg;
    num_mnths++;
			if (num_mnths > 300) {
      	alert("We are interrupting this process to prevent a hang which may result with a very high balance, high interest rate and low monthly payment.\n\nTry entering a higher monthly payment amount." )
				form.mnth_pay.focus()
				form.mnth_pay.select()
				return
      }
    tot_int += fin_chg;
  }
	
// display result
	form.num_months.value = num_mnths;
	form.total_pay.value ="$" + round(init_bal + tot_int);
	form.total_int.value ="$" + round(tot_int);
   }

// round to 2 decimal places
function round(x) {
	return Math.round(x*100)/100;
}

Head

Paste this code into the HEAD section of your HTML document.


<script type="text/javascript" src="creditCardDebtCalculator.js"></script>

Body

Paste this code into the BODY section of your HTML document


<div style="width: 400px;">
<form>
<table border="0" cellspacing="0" cellpadding="0" style="width:80%">
<tbody>
<tr>
<td>Total Credit Card Debt:</td>
<td style="width:150px"><input name="balance" size="12" type="text" style="width:150px"></td>
</tr>
<tr style="background:#eef6f9">
<td>Interest Rate (Annual Percentage):</td>
<td style="width:150px"><input name="interest" size="12" type="text" style="width:150px"></td>
</tr>
<tr>
<td>Current Monthly Payment:</td>
<td style="width:150px"><input name="mnth_pay" size="12" type="text" style="width:150px"></td>
</tr>

<tr>
<td colspan="2" style="text-align:center;padding-top:10px">
<input onclick="calculate(this.form)" type="button" value="Calculate" style="width:220px"> 
<input type="reset" style="width:220px">
</td>
</tr>
<tr>
<td style="padding-top:20px">Months It Will Take To Be Debt Free:</td>
<td style="padding-top:20px"><input name="num_months" size="12" type="text" style="width:150px"></td>
</tr>
<tr style="background:#eef6f9">
<td>Total Amount Payed To Lender:</td>
<td style="width:150px"><input name="total_pay" size="12" type="text" style="width:150px"></td>
</tr>
<tr>

<td>Total Interest Paid To Lender:</td>
<td style="width:150px"><input name="total_int" size="12" type="text" style="width:150px"></td>
</tr>
</tbody>
</table>
</form>
</div>

Leave a Response

(1 comment)

the code is very helpfull but it would be usefull if the notes of execution is given....[br /]once again great codes.........with new logics

sharat Jun 1, 2008

Alphabetical Listing

Tutorials

Ajax Tutorials

Ajax

Buttons

Cookies

CSS

Forms

Games

Generators

Image Effects

Math Related

Miscellaneous

Multimedia

Navigation

Page Details

Password

Snippets

Text Effects

Time & Date

User Details