Add ISMN validator and test cases

README.md

@@ -127,6 +127,7 @@ Validator                               | Description
 **isIPRange(str [, version])**          | check if the string is an IP Range (version 4 or 6).
 **isISBN(str [, options])**             | check if the string is an [ISBN][ISBN].<br/><br/>`options` is an object that has no default.<br/>**Options:**<br/>`version`: ISBN version to compare to. Accepted values are '10' and '13'. If none provided, both will be tested.
 **isISIN(str)**                         | check if the string is an [ISIN][ISIN] (stock/security identifier).
+**isISMN(str)**                         | check if the string is a valid International Standard Music Number (ISMN). Supports both 13-digit and older 10-character ISMNs, allows spaces or hyphens, and checks the check digit.
 **isISO6346(str)**                      | check if the string is a valid [ISO 6346](https://en.wikipedia.org/wiki/ISO_6346) shipping container identification.
 **isISO6391(str)**                      | check if the string is a valid [ISO 639-1][ISO 639-1] language code.
 **isISO8601(str [, options])**          | check if the string is a valid [ISO 8601][ISO 8601] date. <br/>`options` is an object which defaults to `{ strict: false, strictSeparator: false }`. If `strict` is true, date strings with invalid dates like `2009-02-29` will be invalid. If `strictSeparator` is true, date strings with date and time separated by anything other than a T will be invalid.

src/index.js

@@ -79,6 +79,7 @@ import isIdentityCard from './lib/isIdentityCard';
 import isEAN from './lib/isEAN';
 import isISIN from './lib/isISIN';
 import isISBN from './lib/isISBN';
+import isISMN from './lib/isISMN';
 import isISSN from './lib/isISSN';
 import isTaxID from './lib/isTaxID';
 
@@ -201,6 +202,7 @@ const validator = {
   isEAN,
   isISIN,
   isISBN,
+  isISMN,
   isISSN,
   isMobilePhone,
   isMobilePhoneLocales,

src/lib/isISMN.js

@@ -0,0 +1,38 @@
+import assertString from './util/assertString';
+
+export default function isISMN(str) {
+  assertString(str);
+
+  // Check for spaces or hyphens at the beginning, end, or repeated together.
+  if (/^[ -]|[ -]$|[ -]{2}/.test(str)) {
+    return false;
+  }
+
+  // Remove spaces and hyphens so we can check the number.
+  let ismn = str.replace(/[ -]/g, '');
+
+  // Change the older ISMN format to the 13-digit version.
+  if (/^M[0-9]{9}$/.test(ismn)) {
+    ismn = `9790${ismn.slice(1)}`;
+  }
+
+  // Make sure it has 13 digits and starts with 9790.
+  if (!/^9790[0-9]{9}$/.test(ismn)) {
+    return false;
+  }
+
+  // Go through the first 12 digits to calculate the check digit.
+  let sum = 0;
+
+  for (let i = 0; i < 12; i++) {
+    const digit = Number(ismn[i]);
+    const weight = i % 2 === 0 ? 1 : 3;
+    sum += digit * weight;
+  }
+
+  // Find what the last digit should be.
+  const checkDigit = (10 - (sum % 10)) % 10;
+
+  // Check if the last digit matches what we calculated.
+  return checkDigit === Number(ismn[12]);
+}

test/validators.test.js

@@ -7167,6 +7167,64 @@ describe('Validators', () => {
     });
   });
 
+  it('should validate ISMN numbers', () => {
+    test({
+      validator: 'isISMN',
+      valid: [
+        // Modern 13-digit ISMNs
+        '9790260000438',
+        '9790000000001',
+        '9790692006282',
+        '9790345246805',
+
+        // ISMNs with spaces or hyphens
+        '979-0-2600-0043-8',
+        '979 0 2600 0043 8',
+        '979-0-69200-628-2',
+
+        // Older ISMNs starting with M
+        'M571100513',
+        'M692006282',
+        'M345246805',
+        'M-345-24680-5',
+        'M 345 24680 5',
+      ],
+      invalid: [
+        // Numbers with the wrong check digit
+        '9790260000439',
+        '9790692006283',
+        'M692006283',
+
+        // Numbers that start incorrectly
+        '9780260000438',
+        '9791260000438',
+        'A692006282',
+
+        // Numbers that are too short or too long
+        '979026000043',
+        '97902600004388',
+        'M69200628',
+        'M6920062822',
+
+        // Numbers with invalid characters
+        '9790A60000438',
+        'M69200A282',
+        '9790.2600.0043.8',
+        '',
+
+        // Incorrect spaces or hyphens
+        '-9790260000438',
+        '9790260000438-',
+        '979--0-2600-0043-8',
+        'M--345-24680-5',
+      ],
+      error: [
+        null,
+        9790260000438,
+      ],
+    });
+  });
+
   it('should validate ISSNs', () => {
     test({
       validator: 'isISSN',