cdigit

cdigit: Check Digit Algorithms in JS

cdigit - Collection of check digit algorithms implemented in JavaScript

Synopsis

Node.js:

const cdigit = require('cdigit');

// Luhn (a.k.a. Mod 10) algorithm
console.log(cdigit.luhn.compute('1234'));   // '4'
console.log(cdigit.luhn.generate('1234'));  // '12344'
console.log(cdigit.luhn.validate('12344')); // true

Command-line:

# Damm algorithm
npx cdigit --algo damm compute 1234
npx cdigit --algo damm generate 1234
npx cdigit --algo damm validate 12340

Supported Algorithms

Generic Algorithms

Algorithm	cdigit name	Input string	Check character(s)
Luhn	luhn	Numeric (0-9)	1 digit (0-9)
Verhoeff	verhoeff	Numeric (0-9)	1 digit (0-9)
Damm	damm	Numeric (0-9)	1 digit (0-9)

ISO/IEC 7064 Family

ISO/IEC 7064 describes eight generic check digit (character) systems for numeric, alphabetic, and alphanumeric strings. ISO/IEC 7064 specifies two types of systems that use the same algorithm with different parameters: Pure systems (MOD 11-2, MOD 37-2, MOD 97-10, MOD 661-26, and MOD 1271-36) and Hybrid systems (MOD 11-10, MOD 27-26, and MOD 37-36).

Algorithm	cdigit name	Input string	Check character(s)
ISO/IEC 7064, MOD 11-2	mod11_2	Numeric (0-9)	1 digit or 'X' (0-9X)
ISO/IEC 7064, MOD 37-2	mod37_2	Alphanumeric (0-9A-Z)	1 digit, letter, or '*' (0-9A-Z*)
ISO/IEC 7064, MOD 97-10	mod97_10	Numeric (0-9)	2 digits (0-9)
ISO/IEC 7064, MOD 661-26	mod661_26	Alphabetic (A-Z)	2 letters (A-Z)
ISO/IEC 7064, MOD 1271-36	mod1271_36	Alphanumeric (0-9A-Z)	2 digits or letters (0-9A-Z)
ISO/IEC 7064, MOD 11-10	mod11_10	Numeric (0-9)	1 digit (0-9)
ISO/IEC 7064, MOD 27-26	mod27_26	Alphabetic (A-Z)	1 letter (A-Z)
ISO/IEC 7064, MOD 37-36	mod37_36	Alphanumeric (0-9A-Z)	1 digit or letter (0-9A-Z)

GTIN (Global Trade Item Number) Family

GTINs are internationally unified product identification numbers that are often (or historically) referred to as UPC, EAN, ISBN-13, etc. GTINs have several variations in length but share the identical check digit algorithm; therefore, cdigit currently provides only one generic gtin object for GTINs and other GS1 data structures. Note that cdigit.gtin does not check the length or semantic validity of a given GTIN string.

Algorithm	cdigit name	Input string	Check character(s)	Also known as
GTIN-8	gtin	Numeric (0-9)	1 digit (0-9)	EAN-8
GTIN-12	gtin	Numeric (0-9)	1 digit (0-9)	UPC, UPC-A
GTIN-13	gtin	Numeric (0-9)	1 digit (0-9)	EAN, JAN, ISBN-13, etc.
GTIN-14	gtin	Numeric (0-9)	1 digit (0-9)	EAN, UCC-14

Usage - Node.js

Load cdigit and access to algorithm objects by cdigit.name listed in Supported Algorithms section.

const cdigit = require('cdigit');
const algo = cdigit.mod97_10;

Algorithm objects implement the following methods:

validate(numWithCC: string): boolean

Check if a given string is valid according to the algorithm. The argument must be a combined string of check digit(s) and their original number.

console.log(cdigit.mod97_10.validate('123482'));  // true

generate(numWithoutCC: string): string

Generate a valid number string from a given string in accordance with the algorithm. The generated string includes the original string and computed check digit(s) that are combined in the manner specified by the algorithm.

console.log(cdigit.mod97_10.generate('1234'));  // '123482'

compute(numWithoutCC: string): string

Generate check digit(s) from a given number. Unlike generate(), this method returns the check digit(s) only.

console.log(cdigit.mod97_10.compute('1234')); // '82'

See example.js for usage examples.

Usage - Command-line

Usage: cdigit [options] [command]

Options:
  -a, --algo <name>  specify check digit algorithm by name
  -h, --help         output usage information

Commands:
  validate <string>  check if string is valid
  generate <string>  generate valid number from string
  compute <string>   compute check digit from string

-a, --algo <name> option accepts the names listed in Supported Algorithms section and defaults to luhn or the value of CDIGIT_CLI_DEFAULT_ALGO environment variable (if set).

License

Copyright (c) 2018 LiosK

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

See Also

• GitHub repository
• npm package
• typedoc-generated documentation (experimental)