Loan NPM | npm.io

loan

Loan is a tool for representing and performing calculations on loans in JavaScript.

Features

Represent and serialize data about a loan
Calculate payment plans
Effective interest rate
Total loan cost
Amortize a defined loan according to the payment plan
Etc

Example

var Loan = require('loan');

// set up a monthly annuity loan with 120 instalments until settled
var loan = new Loan({
  type: 'annuity',
  pay_every: 'month',
  principal: 100000,
  interest_rate: 0.05,
  invoice_fee: 25,
  instalments: 120
});

// 0.0565
console.log(loan.getEffectiveInterestRate());

Installation

Loan can be installed with npm npm install in your shell should suffice.

Version history

v0.0.1 2016-02-18 Initial (beta) release.

Class documentation

A comprehensive class documentation made with jsdoc is available at loan.tedeh.net together with this readme.

Usage

This section is a friendly showcase of some of the features a loan object has. For more in-depth information, peruse the source code, the tests, or the class documentation

Effective interest rate

Payment Plan

A payment plan is a list of loans relating to the current instance, where every loan in the list corresponds to a

To return a payment plan for a loan instance,

Filtering

Completing unknown values

Sometimes not all values of a given loan are known, and it would be useful to infer the unknowns. Loan has a limited capability (more to come) to do this:

Value	Requirements	Description
`instalments`	1) `principal` 2) `interest_rate` 3) `data.monthly_cost`	Calculate the number of instalments left for an annuity loan

Example calculating instalments given some other values:

var Loan = require('loan');

var loan = new Loan({
  principal: 50000,
  interst_rate: 0.05,
  data: {monthly_cost: 3000}
});

loan.canCalculateUnknown('instalments');
// returns true

loan.calculateUnknown();
// returns an object with a single property "instalments" corresponding to the wanted value

Amortizing

When the as_of date on a loan instance is earlier in time than one (1) pay_every period, shouldAmortize returns true. Running amortize when this is the case returns a copy of the current loan with the present value updated. The as_of date is also updated to correspond to the start of the current pay_every period.

Example amortizing an older loan:

var Loan = require('loan');
var moment = require('moment');

var loan = new Loan({
  interest_rate: 0.01,
  principal: 10000,
  pay_every: 'month',
  instalments: 10,
  type: 'annuity',
  as_of: moment().subtract(3, 'months').toDate()
});

loan.shouldAmortize();
// returns true

loan.amortize();
// returns a copy of loan but with values following three months of amortization

Example fully amortizing a loan:

var Loan = require('loan');
var moment = require('moment');

var loan = new Loan({
  interest_rate: 0.01,
  principal: 10000,
  pay_every: 'month',
  instalments: 2, // only 2 instalments left
  type: 'annuity',
  as_of: moment().subtract(5, 'months').toDate()
});

loan.shouldAmortize();
// returns true

loan.amortize();
// returns a copy of loan with a principal equal to zero