InterestJS

Calculate compound interest in js (browser/node.js/browserify).

Getting Started

Install the module with:

npm install interestjs

or with Bower:

bower install interest-js --save

var Interest = require('interestjs');
var inst     = Interest(singleAmount, months, interestRate, params);

// returns
{ 
  payments  : [
    {
      capital: number,
      interest: number,
      tax: number,
      capitalSum: number,
      sum: number
    }
  ],
  interestSum   : number,
  capitalSum    : number,
  taxSum        : number,
  sum           : number
}

Documentation

Interest(singleAmount, months, interestRate, params)

Arguments

Argument	type	default	Description
singleAmount	number	*required	single saving amount (monthly)
months	number	*required	months of savings
interestRate	number	*required	interest rate in percent (ex. 3.5)
params	object	undefined	parameters

Params object

• tax - persentage tax on interest
• dynamicAmount - function for getting next amount of savings
• startAmount - amount of money put at the begining

Returns

{ 
  installments  : [
    {
      capital     : number,
      interest     : number,
      installment : number,
      remain      : number
    }
  ],
  amount        : number,
  interestSum   : number,
  capitalSum    : number,
  sum           : number
}

Examples

nodejs / browserify example

var Interest  = require('../lib/interest.js');

var interest_1 = new Interest(1000, 12, 5, {tax:19});
console.log(interest_1);
// systematic savings over in 12 montchs with 5% interest rate and interest tax 19% (in poland we have 19%)

Browser example:

<script src="../../lib/interest.js"></script>
<script>
    var interest_1 = new Interest(1000, 12, 5, {tax:19});
</script>

more examples here

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality.

Release History

2015-10-12 v0.1.0

• fixing typo intrest -> interest
• update dependencies

2014-11-10 v0.0.1

• add dynamic amount param to have controll of every saving

2014-11-10 v0.0.1

• init commit

License

Copyright (c) 2014 Grzegorz Klimek
Licensed under the MIT license.