+Luhn

Author: Dmitry Ovsyanko

__tests__/isBankCard.js

@@ -0,0 +1,9 @@
+const {isBankCard} = require ('..')
+
+test ('basic', () => {
+
+	expect (isBankCard ('5062821234567892')).toBeUndefined ()
+	expect (() => isBankCard ('5062821734567892')).toThrow ()
+	
+
+})

index.js

@@ -3,6 +3,7 @@ const {OGRN_13, OGRN_15} = require ('./lib/Horner')
 const {INN_10, INN_12_2, INN_12_1} = require ('./lib/INN')
 const SNILS = require ('./lib/SNILS')
 const BankAcct = require ('./lib/BankAcct')
+const Luhn = require ('./lib/Luhn')
 const {OKPO_8, OKPO_10} = require ('./lib/OKPO')
 class KPP extends Check {constructor () {super (9)}}
 
@@ -38,4 +39,6 @@ module.exports = {
 	isBankAcct : (str, bic)    => new BankAcct ().verify (str, bic),
 	randomBankAcct: (bic, opt) => new BankAcct ().random (bic, opt),
 
+	isBankCard : str  => new Luhn (16).verify (str)
+
 }

lib/Luhn.js

@@ -0,0 +1,34 @@
+const Check = require ('./Check')
+
+module.exports = class extends Check {
+
+	constructor (totalLength) {
+
+		super (totalLength, 1)
+
+		this.modulus1 = 10
+
+	}
+
+	process (str) {
+
+		this.isToDouble = (this.totalLength & 1) === 0
+
+		super.process (str)
+
+		this.sum = 10 - (this.sum % 10)
+
+	}
+	
+	processDigit (pos, digit) {
+
+		if (this.isToDouble) digit <<= 1
+
+		if (digit > 9) digit -= 9
+
+		this.sum += digit
+
+		this.isToDouble = !this.isToDouble
+	}
+		
+}

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "ru-codes",
-  "version": "1.0.4",
+  "version": "1.0.5",
   "description": "ИНН, КПП и т. п.",
   "main": "index.js",
   "files": ["/lib", "/badges"],