You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
23 lines
708 B
23 lines
708 B
import assertString from './util/assertString'; |
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var issn = '^\\d{4}-?\\d{3}[\\dX]$'; |
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export default function isISSN(str) { |
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var options = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : {}; |
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assertString(str); |
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var testIssn = issn; |
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testIssn = options.require_hyphen ? testIssn.replace('?', '') : testIssn; |
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testIssn = options.case_sensitive ? new RegExp(testIssn) : new RegExp(testIssn, 'i'); |
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if (!testIssn.test(str)) { |
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return false; |
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} |
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var digits = str.replace('-', '').toUpperCase(); |
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var checksum = 0; |
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for (var i = 0; i < digits.length; i++) { |
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var digit = digits[i]; |
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checksum += (digit === 'X' ? 10 : +digit) * (8 - i); |
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} |
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return checksum % 11 === 0; |
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} |