loanjs - npm Package Compare versions

Comparing version 1.0.12 to 1.1.0

dist/loan.js

@@ -38,20 +38,62 @@ "use strict";
   /**
+   * @type {import("../types").GetNextInstalmentPartFunction}
+   */
+  function getNextDiminishingInstalment(amount, installmentsNumber, capitalSum, interestRateMonth) {
+    var capital = rnd(amount / installmentsNumber);
+    var interest = rnd((amount - capitalSum) * interestRateMonth);
+    var installment = capital + interest;
+    return {
+      capital: capital,
+      interest: interest,
+      installment: installment
+    };
+  }
+
+  /**
+   * @type {import("../types").GetNextInstalmentPartFunction}
+   */
+  function getNextAnnuityInstalment(amount, installmentsNumber, capitalSum, interestRateMonth) {
+    var z = 1 / (1 + interestRateMonth);
+    var div = (1 - Math.pow(z, installmentsNumber)) * z;
+    var installment = rnd(amount * (1 - z) / div);
+    var interest = rnd((amount - capitalSum) * interestRateMonth);
+    var capital = installment - interest;
+    return {
+      capital: capital,
+      interest: interest,
+      installment: installment
+    };
+  }
+
+  /**
+   * @type {import("../types").GetNextInstalmentPartFunction}
+   */
+  function getNextAnnuityDueInstalment(amount, installmentsNumber, capitalSum, interestRateMonth) {
+    var z = 1 / (1 + interestRateMonth);
+    var div = 1 - Math.pow(z, installmentsNumber);
+    var installment = rnd(amount * (1 - z) / div);
+    var interest = rnd((amount - capitalSum) * interestRateMonth);
+    var capital = installment - interest;
+    return {
+      capital: capital,
+      interest: interest,
+      installment: installment
+    };
+  }
+  var nextInstalmentFnMap = {
+    annuity: getNextAnnuityInstalment,
+    diminishing: getNextDiminishingInstalment,
+    annuityDue: getNextAnnuityDueInstalment
+  };
+
+  /**
    * @type {import("../types").GetNextInstalmentFunction}
    */
-  var getNextInstalment = function getNextInstalment(amount, installmentsNumber, interestRate, diminishing, capitalSum, interestSum) {
-    var capital;
-    var interest;
-    var installment;
-    var irmPow;
+  function getNextInstalment(amount, installmentsNumber, interestRate, loanType, capitalSum, interestSum) {
     var interestRateMonth = interestRate / 1200;
-    if (diminishing) {
-      capital = rnd(amount / installmentsNumber);
-      interest = rnd((amount - capitalSum) * interestRateMonth);
-      installment = capital + interest;
-    } else {
-      irmPow = Math.pow(1 + interestRateMonth, installmentsNumber);
-      installment = rnd(amount * (interestRateMonth * irmPow / (irmPow - 1)));
-      interest = rnd((amount - capitalSum) * interestRateMonth);
-      capital = installment - interest;
-    }
+    var nextInstalmentFn = typeof loanType === 'function' ? loanType : nextInstalmentFnMap[loanType] || getNextAnnuityInstalment;
+    var _nextInstalmentFn = nextInstalmentFn(amount, installmentsNumber, capitalSum, interestRateMonth),
+      capital = _nextInstalmentFn.capital,
+      interest = _nextInstalmentFn.interest,
+      installment = _nextInstalmentFn.installment;
     return {
@@ -64,3 +106,3 @@ capital: capital,
     };
-  };
+  }
 
@@ -71,3 +113,3 @@ /**
   function Loan(amount, installmentsNumber, interestRate) {
-    var diminishing = arguments.length > 3 && arguments[3] !== undefined ? arguments[3] : false;
+    var loanTypeWithBool = arguments.length > 3 && arguments[3] !== undefined ? arguments[3] : 'annuity';
     if (!amount || amount <= 0 || !installmentsNumber || installmentsNumber <= 0 || !interestRate || interestRate <= 0) {
@@ -77,2 +119,3 @@ throw new Error("wrong parameters: ".concat(amount, " ").concat(installmentsNumber, " ").concat(interestRate));
     var installments = [];
+    var loanType = typeof loanTypeWithBool === 'boolean' ? loanTypeFromBool(loanTypeWithBool) : loanTypeWithBool;
     var interestSum = 0;
@@ -82,3 +125,3 @@ var capitalSum = 0;
     for (var i = 0; i < installmentsNumber; i++) {
-      var inst = getNextInstalment(amount, installmentsNumber, interestRate, diminishing, capitalSum, interestSum);
+      var inst = getNextInstalment(amount, installmentsNumber, interestRate, loanType, capitalSum, interestSum);
       sum += inst.installment;
@@ -104,2 +147,10 @@ capitalSum += inst.capital;
 
+  /**
+   * @param {boolean} boolType
+   * @returns {import("../types").LoanType}
+   */
+  function loanTypeFromBool(boolType) {
+    return boolType ? 'diminishing' : 'annuity';
+  }
+
   /* istanbul ignore next */
@@ -106,0 +157,0 @@ if (typeof window !== 'undefined') {

dist/loan.min.js

@@ -1,1 +0,1 @@
-"use strict";function _typeof(n){return(_typeof="function"==typeof Symbol&&"symbol"==typeof Symbol.iterator?function(n){return typeof n}:function(n){return n&&"function"==typeof Symbol&&n.constructor===Symbol&&n!==Symbol.prototype?"symbol":typeof n})(n)}!function(n){"object"===("undefined"==typeof exports?"undefined":_typeof(exports))&&"undefined"!=typeof module?module.exports=n():"function"==typeof define&&define.amd?define(n):("undefined"!=typeof globalThis?globalThis:self).loan=n()}(function(){function w(n){return Math.round(100*n)/100}var n;function t(n,t,e){var o=3<arguments.length&&void 0!==arguments[3]&&arguments[3];if(!n||n<=0||!t||t<=0||!e||e<=0)throw new Error("wrong parameters: ".concat(n," ").concat(t," ").concat(e));for(var r,i,a,f,u,l,p,c,m=[],s=0,d=0,y=0,S=0;S<t;S++){r=n,b=t,i=e,f=d,u=s,c=p=l=void 0,i/=1200,(a=o)?c=(l=w(r/b))+(p=w((r-f)*i)):l=(c=w(r*(i*(a=Math.pow(1+i,b))/(a-1))))-(p=w((r-f)*i));var b={capital:l,interest:p,installment:c,remain:r-f-l,interestSum:u+p};y+=b.installment,d+=b.capital,s+=b.interest,S===t-1&&(d+=b.remain,y+=b.remain,b.remain=0),m.push(b)}return{installments:m,amount:w(n),interestSum:w(s),capitalSum:w(d),sum:w(y)}}return"undefined"!=typeof window&&((n=window).LoanJS||(n.LoanJS={}),n.LoanJS.Loan=t),t});
+"use strict";function _typeof(n){return(_typeof="function"==typeof Symbol&&"symbol"==typeof Symbol.iterator?function(n){return typeof n}:function(n){return n&&"function"==typeof Symbol&&n.constructor===Symbol&&n!==Symbol.prototype?"symbol":typeof n})(n)}!function(n){"object"===("undefined"==typeof exports?"undefined":_typeof(exports))&&"undefined"!=typeof module?module.exports=n():"function"==typeof define&&define.amd?define(n):("undefined"!=typeof globalThis?globalThis:self).loan=n()}(function(){function b(n){return Math.round(100*n)/100}function S(n,t,e,o){var i=1/(1+o),t=b(n*(1-i)/((1-Math.pow(i,t))*i)),i=b((n-e)*o);return{capital:t-i,interest:i,installment:t}}var n,h={annuity:S,diminishing:function(n,t,e,o){return t=b(n/t),n=b((n-e)*o),{capital:t,interest:n,installment:t+n}},annuityDue:function(n,t,e,o){var i=b(n*(1-(i=1/(1+o)))/(1-Math.pow(i,t))),t=b((n-e)*o);return{capital:i-t,interest:t,installment:i}}};function t(n,t,e){var o=3<arguments.length&&void 0!==arguments[3]?arguments[3]:"annuity";if(!n||n<=0||!t||t<=0||!e||e<=0)throw new Error("wrong parameters: ".concat(n," ").concat(t," ").concat(e));for(var i,a,r,u,f,l=[],s="boolean"==typeof o?o?"diminishing":"annuity":o,c=0,p=0,m=0,y=0;y<t;y++){i=n,a=t,r=e,u=p,f=c,d=("function"==typeof(d=s)?d:h[d]||S)(i,a,u,r/1200),a=d.capital,r=d.interest;var d={capital:a,interest:r,installment:d.installment,remain:i-u-a,interestSum:f+r};m+=d.installment,p+=d.capital,c+=d.interest,y===t-1&&(p+=d.remain,m+=d.remain,d.remain=0),l.push(d)}return{installments:l,amount:b(n),interestSum:b(c),capitalSum:b(p),sum:b(m)}}return"undefined"!=typeof window&&((n=window).LoanJS||(n.LoanJS={}),n.LoanJS.Loan=t),t});

lib/loan.js

@@ -13,29 +13,59 @@ /*
 /**
+ * @type {import("../types").GetNextInstalmentPartFunction}
+ */
+function getNextDiminishingInstalment (amount, installmentsNumber, capitalSum, interestRateMonth) {
+  const capital = rnd(amount / installmentsNumber)
+  const interest = rnd((amount - capitalSum) * interestRateMonth)
+  const installment = capital + interest
+
+  return { capital, interest, installment }
+}
+
+/**
+ * @type {import("../types").GetNextInstalmentPartFunction}
+ */
+function getNextAnnuityInstalment (amount, installmentsNumber, capitalSum, interestRateMonth) {
+  const z = 1 / (1 + interestRateMonth)
+  const div = (1 - Math.pow(z, installmentsNumber)) * z
+  const installment = rnd(amount * (1 - z) / div)
+  const interest = rnd((amount - capitalSum) * interestRateMonth)
+  const capital = installment - interest
+
+  return { capital, interest, installment }
+}
+
+/**
+ * @type {import("../types").GetNextInstalmentPartFunction}
+ */
+function getNextAnnuityDueInstalment (amount, installmentsNumber, capitalSum, interestRateMonth) {
+  const z = 1 / (1 + interestRateMonth)
+  const div = (1 - Math.pow(z, installmentsNumber))
+  const installment = rnd(amount * (1 - z) / div)
+  const interest = rnd((amount - capitalSum) * interestRateMonth)
+  const capital = installment - interest
+
+  return { capital, interest, installment }
+}
+
+const nextInstalmentFnMap = {
+  annuity: getNextAnnuityInstalment,
+  diminishing: getNextDiminishingInstalment,
+  annuityDue: getNextAnnuityDueInstalment
+}
+
+/**
  * @type {import("../types").GetNextInstalmentFunction}
  */
-const getNextInstalment = (
+function getNextInstalment (
   amount,
   installmentsNumber,
   interestRate,
-  diminishing,
+  loanType,
   capitalSum,
   interestSum
-) => {
-  let capital
-  let interest
-  let installment
-  let irmPow
+) {
   const interestRateMonth = interestRate / 1200
+  const nextInstalmentFn = typeof loanType === 'function' ? loanType : nextInstalmentFnMap[loanType] || getNextAnnuityInstalment
+  const { capital, interest, installment } = nextInstalmentFn(amount, installmentsNumber, capitalSum, interestRateMonth)
 
-  if (diminishing) {
-    capital = rnd(amount / installmentsNumber)
-    interest = rnd((amount - capitalSum) * interestRateMonth)
-    installment = capital + interest
-  } else {
-    irmPow = Math.pow(1 + interestRateMonth, installmentsNumber)
-    installment = rnd(amount * ((interestRateMonth * irmPow) / (irmPow - 1)))
-    interest = rnd((amount - capitalSum) * interestRateMonth)
-    capital = installment - interest
-  }
-
   return {
@@ -53,3 +83,3 @@ capital,
  */
-function Loan (amount, installmentsNumber, interestRate, diminishing = false) {
+function Loan (amount, installmentsNumber, interestRate, loanTypeWithBool = 'annuity') {
   if (
@@ -69,2 +99,3 @@ !amount ||
   const installments = []
+  const loanType = typeof loanTypeWithBool === 'boolean' ? loanTypeFromBool(loanTypeWithBool) : loanTypeWithBool
   let interestSum = 0
@@ -79,3 +110,3 @@ let capitalSum = 0
       interestRate,
-      diminishing,
+      loanType,
       capitalSum,
@@ -107,2 +138,10 @@ interestSum
 
+/**
+ * @param {boolean} boolType
+ * @returns {import("../types").LoanType}
+ */
+function loanTypeFromBool (boolType) {
+  return boolType ? 'diminishing' : 'annuity'
+}
+
 /* istanbul ignore next */
@@ -109,0 +148,0 @@ if (typeof window !== 'undefined') {

lib/loan.test.js

@@ -9,3 +9,3 @@ /* eslint-env jest */
 
-test('loan js should count loan with equal instalment', () => {
+test('loan js should count loan with equal instalment (annuity)', () => {
   const loan = Loan(20000, 30 * 12, 5, false)
@@ -25,2 +25,19 @@
 
+test('loan js should count loan with equal instalment (annuity) as default', () => {
+  /** @type any */
+  const LoanToTest = Loan
+  const loan = LoanToTest(20000, 30 * 12, 5, 'wrong-type-as-annuity')
+
+  expect(loan).toBeDefined()
+  expect(loan.installments.length).toBe(30 * 12)
+  expect(loan.installments[0].installment).toBe(107.36)
+  expect(loan.installments[30 * 12 - 1].installment).toBe(107.36)
+  expect(loan.amount).toBe(20000)
+  expect(loan.capitalSum).toBe(20000)
+  expect(loan.interestSum).toBe(18653.27)
+  expect(loan.sum).toBe(38653.27)
+
+  expect(rnd(loan.capitalSum + loan.interestSum)).toBe(loan.sum)
+})
+
 test('loan js should count loan with dismissing instalment', () => {
@@ -42,2 +59,44 @@ const loan = Loan(20000, 30 * 12, 5, true)
 
+test('loan js should count loan with any loanType function', () => {
+  /**
+   * @type {import("../types").GetNextInstalmentPartFunction}
+   */
+  function getNext10Instalment (amount, installmentsNumber, capitalSum, interestRateMonth) {
+    const capital = rnd(amount / installmentsNumber)
+    const interest = 10
+    const installment = capital + interest
+
+    return { capital, interest, installment }
+  }
+  const loan = Loan(20000, 30 * 12, 5, getNext10Instalment)
+
+  expect(loan).toBeDefined()
+  expect(loan.installments.length).toBe(30 * 12)
+
+  expect(loan.installments[0].installment).toBe(65.56)
+  expect(loan.installments[30 * 12 - 1].installment).toBe(65.56)
+  expect(loan.amount).toBe(20000)
+  expect(loan.capitalSum).toBe(20000)
+  expect(loan.interestSum).toBe(3600)
+  expect(loan.sum).toBe(23600)
+
+  expect(rnd(loan.capitalSum + loan.interestSum)).toBe(loan.sum)
+})
+
+test('loan js should count loan with annuity due function', () => {
+  const loan = Loan(30000, 30 * 12, 5, 'annuityDue')
+
+  expect(loan).toBeDefined()
+  expect(loan.installments.length).toBe(360)
+
+  expect(loan.installments[0].installment).toBe(160.38)
+  expect(loan.installments[23].installment).toBe(160.38)
+  expect(loan.amount).toBe(30000)
+  expect(loan.capitalSum).toBe(30000)
+  expect(loan.interestSum).toBe(28291.49)
+  expect(loan.sum).toBe(58291.49)
+
+  expect(rnd(loan.capitalSum + loan.interestSum)).toBe(loan.sum)
+})
+
 test('loan js should throw on wrong params', () => {
@@ -44,0 +103,0 @@ /** @type any */

package.json

 {
   "name": "loanjs",
-  "version": "1.0.12",
+  "version": "1.1.0",
   "main": "LoanJS.js",
@@ -5,0 +5,0 @@ "description": "Calculate loan in js (browser/node.js) for equal installments, installments decreasing, the sum of interest, etc.",

README.md

@@ -7,9 +7,8 @@ # LoanJS
 
-Super **small** (**~500B**) and **fast** module to calculate loan in js (browser/node.js) for **equal**/**decreasing** installments, the **sum of interest**, etc.
+Super **small** (**~500B**) and **fast** module to calculate loan in js (browser/node.js) for **equal**/**decreasing**/**annuity**/**annuityDue** installments, the **sum of interest**, etc, with TypeScript support
 
-Now with TypeScript support
-
 ## Getting Started
 
-Install the module with:
+Install with:
+
 ```
@@ -19,7 +18,2 @@ npm install loanjs
 
-or Bower:
-```
-bower install loan-js --save
-```
-
 #### Calculating Loan:
@@ -35,3 +29,3 @@ ```js
   5,    // interest rate
-  true  // diminishing
+  'annuity'  // loanType: 'annuity' | 'annuityDue' | 'diminishing' | GetNextInstalmentPartFunction
 );
@@ -59,12 +53,27 @@ /** returns
 ### Loan
-LoanJS.Loan(amount, installmentsNumber, interestRate, diminishing)
+LoanJS.Loan(amount, installmentsNumber, interestRate, loanType)
 
 ### Arguments
-| Argument           | type   | default   | Description
-| ------------------ | ------ | --------- | ------------------
-| amount             | number | *required | full amount of Loan
-| installmentsNumber | number | *required | how many installments will be (in months)
-| interestRate       | number | *required | interest rate in percent (ex. 3.5)
-| diminishing        | bool   | false     | if installments will be - true: diminishing; false: equal/annuity
+| Argument           | type           | default   | Description
+| ------------------ | -------------- | --------- | ------------------
+| amount             | number         | *required | full amount of Loan
+| installmentsNumber | number         | *required | how many installments will be (in months)
+| interestRate       | number         | *required | interest rate in percent (ex. 3.5)
+| loanType           | string or fn   | 'annuity' | 'annuity' | 'annuityDue' | 'diminishing' | GetNextInstalmentPartFunction
 
+```ts
+interface InstallmentPart {
+  capital: number;
+  interest: number;
+  installment: number;
+}
+
+type GetNextInstalmentPartFunction = (
+  amount: number,
+  installmentsNumber: number,
+  interestRateMonth: number,
+  capitalSum: number
+) => InstallmentPart;
+```
+
 ### Returns
@@ -90,15 +99,38 @@ ```js
 
-nodejs / browserify example
+### typescript example
+
+```ts
+import { Loan } from 'loanjs';
+
+const annuityLoan = new Loan(1000, 12, 5, 'annuity');
+
+const annuityDueLoan = new Loan(1000, 12, 5, 'annuityDue');
+
+const diminishingLoan = new Loan(1000, 12, 5, 'diminishing');
+
+const customInstalmentLoan = new Loan(1000, 12, 5, getNext10Instalment);
+function getNext10Instalment (amount: number, installmentsNumber: number, capitalSum: number, interestRateMonth: number) {
+  const capital = rnd(amount / installmentsNumber);
+  const interest = 10;
+  const installment = capital + interest;
+
+  return { capital, interest, installment };
+}
+```
+
+### nodejs example
+
 ```js
-
+import { Loan } from 'loanjs';
+// or
 const { Loan } = require('loanjs');
 
-const loan_1 = new Loan(1000, 12, 5, true);
-// loan on 1 000($) in 12 diminishing installments (ex. months) with 5% interest rate
+const loan_1 = new Loan(1000, 12, 5, 'diminishing');
+// loan on 1 000($) in 12 loanType installments (ex. months) with 5% interest rate
 
-const loan_2 = new Loan(500000, 360, 3.5);
+const loan_2 = new Loan(500000, 360, 3.5, 'annuity');
 // loan on 500 000($) in 360 equal installments (30 years) with 3.5% interest rate
 ```
 
-Browser example:
+### Browser example:
 > You can also render loan as html table
@@ -110,5 +142,5 @@
 <script>
-    var loan = new LoanJS.Loan(1000, 12, 5, true);
+    const loan = new LoanJS.Loan(1000, 12, 5, 'annuity');
 
-    var div = document.createElement("div");
+    const div = document.createElement("div");
     div.innerHTML = LoanJS.loanToHtmlTable(loan); // loan rendering as html table string
@@ -131,2 +163,8 @@ document.body.appendChild(div);
 
+#### 2023-06-23 v1.1.0
+ * add `annuityDue` interest rate loan type
+ * changing the fourth argument `diminishing` to `loanType` (`annuity` | `diminishing` | `annuityDue`), with backward compatibility (false == 'annuity', true == 'diminishing')
+ * refactor getNextInstalment to be open for extensions
+ * add option to provide function to loanType to customize instalments counting
+
 #### 2023-06-23 v1.0.11
@@ -133,0 +171,0 @@ * add TypeScript types

types.d.ts

@@ -21,3 +21,3 @@ export interface Installment {
   interestRate: number,
-  diminishing: boolean,
+  loanType: LoanType,
   capitalSum: number,
@@ -27,2 +27,17 @@ interestSum: number
 
+export interface InstallmentPart {
+  capital: number;
+  interest: number;
+  installment: number;
+}
+
+export type GetNextInstalmentPartFunction = (
+  amount: number,
+  installmentsNumber: number,
+  interestRateMonth: number,
+  capitalSum: number
+) => InstallmentPart;
+
+export type LoanType = 'annuity' | 'annuityDue' | 'diminishing' | GetNextInstalmentPartFunction
+
 export type LoanFunction = (
@@ -32,3 +47,3 @@ amount: number,
   interestRate: number,
-  diminishing = false
+  loanType: LoanType | false | true = 'annuity'
 ) => LoanInstance;
@@ -35,0 +50,0 @@

No alert changes

Improved metrics

Total package byte prevSize

34773

27.65%

Lines of code

680

25.46%

Number of lines in readme file

192

24.68%

No dependency changes