A zero-dependency Node.js module for calculating a numeric check digit for alphanumeric strings. The exported luhn() function uses the Luhn algorithm to calculate a check digit based on an input string.

Node.js

const { luhn } = require("@prm/luhn")

luhn("Z2N 9Z3 F0 K3") // returns 2

SQL

SELECT luhn("1245496594") -- returns 3

npm run test