loan-extended

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

Table of contents

• loan-extended
  • Table of contents
  • Features
  • Example
  • Installation
  • Version history
  • Class documentation
  • Usage
    • Effective interest rate
    • Payment Plan
    • Filtering
    • Completing unknown values
    • Amortizing
  • Contributing

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
• Deferred
• Balloon Payment

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,
  // ballon_at: 60
});

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

Installation

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

Version history

• v0.0.43 2023-06-27 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][#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

Contributing

Fork of tedeh's loan

requests on Github is most welcome.

Please make sure to follow the style of the project, lint your code with make lint, and test it with make test before submitting a patch.