music-codes/dist/utils.js

Small library for music codes (ISRC, ISWC, UPC)

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.getLuhnCheckDigit = getLuhnCheckDigit;
exports.raise = raise;
const errors_js_1 = require("./errors.js");
/**
 * Naive implementation of Luhn algorithm for GTIN check digit
 * Does not check for valid code length
 * @see https://www.gs1.org/services/how-calculate-check-digit-manually
 * @see https://rosettacode.org/wiki/Luhn_test_of_credit_card_numbers#JavaScript
 */
function getLuhnCheckDigit(code) {
    const str = String(code);
    if (!/^\d+$/.test(str))
        throw new errors_js_1.CodeValidationError(`Invalid code: ${str}`);
    const cd = str
        .split('')
        .reverse()
        .reduce((acc, v, idx) => {
        return acc + (idx % 2 ? 1 : 3) * Number.parseInt(v);
    }, 0) % 10;
    return cd === 0 ? 0 : 10 - cd;
}
function raise(message) {
    throw new errors_js_1.InvalidStateError(message);
}
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