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) 2018-2021 LiosK

Licensed under either of

• Apache License, Version 2.0
• MIT license

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

See Also

• GitHub repository
• npm package