项目作者: alfredmyers

项目描述 :
Calculates Luhn Mod N check values
高级语言: JavaScript
项目地址: git://github.com/alfredmyers/calculate-luhn-mod-n.git
创建时间: 2019-04-05T15:15:24Z
项目社区:https://github.com/alfredmyers/calculate-luhn-mod-n

开源协议:MIT License

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calculate-luhn-mod-n

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Node.js Package

Calculates Luhn Mod N check values

Code based on https://en.wikipedia.org/wiki/Luhn_mod_N_algorithm
with minimal modifications.

Installing

  1. npm install calculate-luhn-mod-n

API

Parameters

Parameter Description
codePointFromCharacter Function to obtain a code point from a character
characterFromCodePoint Function to obtain a character from a code point
n Number of valid characters
input Input string

Using

The following example is based on the one found at https://en.wikipedia.org/wiki/Luhn_mod_N_algorithm

  1. const map = 'abcdef'; // Character to code-point map
  2. const calculateLuhnModN = require('calculate-luhn-mod-n');
  3. const checkCharacter = calculateLuhnModN(character => map.indexOf(character), codePoint => map[codePoint], map.length, 'abcdef'))
  4. // checkCharacter === 'e'

The following example uses JavaScript native functions (parseInt and toString) to do the mapping based on radix/mod 36.

  1. const calculateLuhnModN = require('calculate-luhn-mod-n');
  2. function appendLuhnMod36(input) {
  3. const radix = 36;
  4. return input + calculateLuhnModN(character => Number.parseInt(character, radix), codePoint => codePoint.toString(radix).toUpperCase(), radix, input);
  5. }
  6. const output = appendLuhnMod36('1134806PJFB000010013CD18');
  7. // output === '1134806PJFB000010013CD18D'

The following example builds upon the previous one and demonstrates a possible way to do validation against an arbitrary regular expression before calculating the check character.

  1. const calculateLuhnModN = require('calculate-luhn-mod-n');
  2. function appendLuhnMod36(input) {
  3. const radix = 36;
  4. const pattern = /^([A-Z]|\d){4}\d{3}([A-Z]|\d){15}\d{2}$/;
  5. if (!pattern.test(input)) {
  6. throw new Error('Invalid identifier format!');
  7. }
  8. return input + calculateLuhnModN(character => Number.parseInt(character, radix), codePoint => codePoint.toString(radix).toUpperCase(), radix, input);
  9. }
  10. const output = appendLuhnMod36('1134806PJFB000010013CD18');
  11. // output === '1134806PJFB000010013CD18D'