bot-28/node/node_modules/validator/es/lib/isISBN.js

import assertString from './util/assertString';
var possibleIsbn10 = /^(?:[0-9]{9}X|[0-9]{10})$/;
var possibleIsbn13 = /^(?:[0-9]{13})$/;
var factor = [1, 3];
export default function isISBN(isbn, options) {
  assertString(isbn);

  // For backwards compatibility:
  // isISBN(str [, version]), i.e. `options` could be used as argument for the legacy `version`
  var version = String((options === null || options === void 0 ? void 0 : options.version) || options);
  if (!(options !== null && options !== void 0 && options.version || options)) {
    return isISBN(isbn, {
      version: 10
    }) || isISBN(isbn, {
      version: 13
    });
  }
  var sanitizedIsbn = isbn.replace(/[\s-]+/g, '');
  var checksum = 0;
  if (version === '10') {
    if (!possibleIsbn10.test(sanitizedIsbn)) {
      return false;
    }
    for (var i = 0; i < version - 1; i++) {
      checksum += (i + 1) * sanitizedIsbn.charAt(i);
    }
    if (sanitizedIsbn.charAt(9) === 'X') {
      checksum += 10 * 10;
    } else {
      checksum += 10 * sanitizedIsbn.charAt(9);
    }
    if (checksum % 11 === 0) {
      return true;
    }
  } else if (version === '13') {
    if (!possibleIsbn13.test(sanitizedIsbn)) {
      return false;
    }
    for (var _i = 0; _i < 12; _i++) {
      checksum += factor[_i % 2] * sanitizedIsbn.charAt(_i);
    }
    if (sanitizedIsbn.charAt(12) - (10 - checksum % 10) % 10 === 0) {
      return true;
    }
  }
  return false;
}