verhoeff-algorithm/index.js

A TypeScript implementation of the Verhoeff algorithm.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.isValidVerhoeff = isValidVerhoeff;
const multiplicationTable = [
    [0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
    [1, 2, 3, 4, 0, 6, 7, 8, 9, 5],
    [2, 3, 4, 0, 1, 7, 8, 9, 5, 6],
    [3, 4, 0, 1, 2, 8, 9, 5, 6, 7],
    [4, 0, 1, 2, 3, 9, 5, 6, 7, 8],
    [5, 9, 8, 7, 6, 0, 4, 3, 2, 1],
    [6, 5, 9, 8, 7, 1, 0, 4, 3, 2],
    [7, 6, 5, 9, 8, 2, 1, 0, 4, 3],
    [8, 7, 6, 5, 9, 3, 2, 1, 0, 4],
    [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
];
const permutationTable = [
    [0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
    [1, 5, 7, 6, 2, 8, 3, 0, 9, 4],
    [5, 8, 0, 3, 7, 9, 6, 1, 4, 2],
    [8, 9, 1, 6, 0, 4, 3, 5, 2, 7],
    [9, 4, 5, 3, 1, 2, 6, 8, 7, 0],
    [4, 2, 8, 6, 5, 7, 3, 9, 0, 1],
    [2, 7, 9, 3, 8, 0, 6, 4, 1, 5],
    [7, 0, 4, 6, 9, 1, 3, 2, 5, 8]
];
/**
* Calculates the Verhoeff checksum for a given number array.
* @param numberArray An array of digits representing the number.
* @returns The checksum value.
*/
function calculateChecksum(numberArray) {
    let c = 0;
    const invertedArray = numberArray.slice().reverse();
    invertedArray.forEach((val, i) => {
        c = multiplicationTable[c][permutationTable[i % 8][val]];
    });
    return c;
}
/**
* Validates if the given number passes the Verhoeff check.
* @param number A string representing the number to check.
* @returns A boolean indicating if the number is valid.
*/
function isValidVerhoeff(number) {
    const numberArray = number.split("").map(Number);
    return calculateChecksum(numberArray) === 0;
}