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isISBN.js
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isISBN.js
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import assertString from './util/assertString';
const isbn10Maybe = /^(?:[0-9]{9}X|[0-9]{10})$/;
const isbn13Maybe = /^(?:[0-9]{13})$/;
const factor = [1, 3];
export default function isISBN(str, version = '') {
assertString(str);
version = String(version);
if (!version) {
return isISBN(str, 10) || isISBN(str, 13);
}
const sanitized = str.replace(/[\s-]+/g, '');
let checksum = 0;
let i;
if (version === '10') {
if (!isbn10Maybe.test(sanitized)) {
return false;
}
for (i = 0; i < 9; i++) {
checksum += (i + 1) * sanitized.charAt(i);
}
if (sanitized.charAt(9) === 'X') {
checksum += 10 * 10;
} else {
checksum += 10 * sanitized.charAt(9);
}
if ((checksum % 11) === 0) {
return !!sanitized;
}
} else if (version === '13') {
if (!isbn13Maybe.test(sanitized)) {
return false;
}
for (i = 0; i < 12; i++) {
checksum += factor[i % 2] * sanitized.charAt(i);
}
if (sanitized.charAt(12) - ((10 - (checksum % 10)) % 10) === 0) {
return !!sanitized;
}
}
return false;
}