From d0b3bb3d771325a2cf6271345f1634ccec51abd1 Mon Sep 17 00:00:00 2001
From: Robin van der Vliet <info@robinvandervliet.com>
Date: Thu, 6 Jul 2023 00:35:58 +0200
Subject: [PATCH 01/11] Add ISBN method to commerce module

---
 src/modules/commerce/index.ts | 147 ++++++++++++++++++++++++++++++++++
 1 file changed, 147 insertions(+)

diff --git a/src/modules/commerce/index.ts b/src/modules/commerce/index.ts
index 89f4771134b..6e9403e8aae 100644
--- a/src/modules/commerce/index.ts
+++ b/src/modules/commerce/index.ts
@@ -1,6 +1,76 @@
 import type { Faker } from '../../faker';
 import { deprecated } from '../../internal/deprecated';
 
+// Source for official prefixes: https://www.isbn-international.org/range_file_generation
+const ISBN_LENGTH_RULES: { [key: string]: Array<[number, number]> } = {
+  '0': [
+    [1999999, 2],
+    [2279999, 3],
+    [2289999, 4],
+    [3689999, 3],
+    [3699999, 4],
+    [6389999, 3],
+    [6397999, 4],
+    [6399999, 7],
+    [6449999, 3],
+    [6459999, 7],
+    [6479999, 3],
+    [6489999, 7],
+    [6549999, 3],
+    [6559999, 4],
+    [6999999, 3],
+    [8499999, 4],
+    [8999999, 5],
+    [9499999, 6],
+    [9999999, 7],
+  ],
+  '1': [
+    [99999, 3],
+    [299999, 2],
+    [349999, 3],
+    [399999, 4],
+    [499999, 3],
+    [699999, 2],
+    [999999, 4],
+    [3979999, 3],
+    [5499999, 4],
+    [6499999, 5],
+    [6799999, 4],
+    [6859999, 5],
+    [7139999, 4],
+    [7169999, 3],
+    [7319999, 4],
+    [7399999, 7],
+    [7749999, 5],
+    [7753999, 7],
+    [7763999, 5],
+    [7764999, 7],
+    [7769999, 5],
+    [7782999, 7],
+    [7899999, 5],
+    [7999999, 4],
+    [8004999, 5],
+    [8049999, 5],
+    [8379999, 5],
+    [8384999, 7],
+    [8671999, 5],
+    [8675999, 4],
+    [8697999, 5],
+    [9159999, 6],
+    [9165059, 7],
+    [9168699, 6],
+    [9169079, 7],
+    [9195999, 6],
+    [9196549, 7],
+    [9729999, 6],
+    [9877999, 4],
+    [9911499, 6],
+    [9911999, 7],
+    [9989899, 6],
+    [9999999, 7],
+  ],
+};
+
 /**
  * Module to generate commerce and product related entries.
  *
@@ -266,4 +336,81 @@ export class CommerceModule {
       this.faker.definitions.commerce.product_description
     );
   }
+
+  /**
+   * Returns a random [ISBN](https://en.wikipedia.org/wiki/ISBN) identifier.
+   *
+   * @param options The variant to return or an options object. Defaults to `{}`.
+   * @param options.variant The variant to return. Can be either `10` (10-digit format)
+   * or `13` (13-digit format). Defaults to `13`.
+   * @param options.separator The separator to use in the format. Defaults to `'-'`.
+   *
+   * @example
+   * faker.commerce.isbn() // '978-0-692-82459-7'
+   * faker.commerce.isbn(10) // '1-155-36404-X'
+   * faker.commerce.isbn(13) // '978-1-60808-867-6'
+   * faker.commerce.isbn({ separator: ' ' }) // '978 0 452 81498 1'
+   * faker.commerce.isbn({ variant: 10, separator: ' ' }) // '0 940319 49 7'
+   * faker.commerce.isbn({ variant: 13, separator: ' ' }) // '978 1 6618 9122 0'
+   *
+   * @since 8.0.0
+   */
+  isbn(
+    options:
+      | 10
+      | 13
+      | {
+          /**
+           * The variant of the identifier to return.
+           * Can be either `10` (10-digit format)
+           * or `13` (13-digit format).
+           *
+           * @default 13
+           */
+          variant?: 10 | 13;
+
+          /**
+           * The separator to use in the format.
+           *
+           * @default '-'
+           */
+          separator?: string;
+        } = {}
+  ): string {
+    if (typeof options === 'number') {
+      options = { variant: options };
+    }
+
+    const { variant = 13, separator = '-' } = options;
+
+    const prefix = '978';
+    const group: string = this.faker.number.int({ min: 0, max: 1 }).toString();
+    const element: string = this.faker.string.numeric(8);
+
+    const registrantLength: number = ISBN_LENGTH_RULES[group].find(
+      ([key]): boolean => parseInt(element.slice(0, -1)) <= key
+    )[1];
+
+    const registrant: string = element.slice(0, registrantLength);
+    const publication: string = element.slice(registrantLength);
+
+    const data: string[] = [prefix, group, registrant, publication];
+    if (variant === 10) {
+      data.shift();
+    }
+
+    const isbn: string = data.join('');
+
+    let checksum = 0;
+    for (let i = 0; i < variant - 1; i++) {
+      const weight: number = variant === 10 ? i + 1 : i % 2 ? 3 : 1;
+      checksum += weight * parseInt(isbn[i]);
+    }
+
+    checksum = variant === 10 ? checksum % 11 : (10 - (checksum % 10)) % 10;
+
+    data.push(checksum === 10 ? 'X' : checksum.toString());
+
+    return data.join(separator);
+  }
 }

From e6d8bdb0fef6c02419be5f1d17689729e5464be7 Mon Sep 17 00:00:00 2001
From: Robin van der Vliet <info@robinvandervliet.com>
Date: Thu, 6 Jul 2023 00:36:04 +0200
Subject: [PATCH 02/11] Add unit tests for ISBN method

---
 test/commerce.spec.ts | 49 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/test/commerce.spec.ts b/test/commerce.spec.ts
index 743aa58b38d..bd65b9be294 100644
--- a/test/commerce.spec.ts
+++ b/test/commerce.spec.ts
@@ -158,6 +158,55 @@ describe('commerce', () => {
           );
         });
       });
+
+      describe(`isbn()`, () => {
+        it('should return ISBN-13 with hyphen separators when not passing arguments', () => {
+          const isbn = faker.commerce.isbn();
+
+          expect(isbn).toBeTruthy();
+          expect(isbn).toBeTypeOf('string');
+          expect(
+            isbn,
+            'The expected match should be ISBN-13 with hyphens'
+          ).toMatch(/^978-[01]-[\d-]{9}-\d$/);
+        });
+
+        it('should return ISBN-10 with hyphen separators when passing variant 10 as argument', () => {
+          const isbn = faker.commerce.isbn(10);
+
+          expect(
+            isbn,
+            'The expected match should be ISBN-10 with hyphens'
+          ).toMatch(/^[01]-[\d-]{9}-[\dX]$/);
+        });
+
+        it('should return ISBN-13 with hyphen separators when passing variant 13 as argument', () => {
+          const isbn = faker.commerce.isbn(13);
+
+          expect(
+            isbn,
+            'The expected match should be ISBN-13 with hyphens'
+          ).toMatch(/^978-[01]-[\d-]{9}-\d$/);
+        });
+
+        it('should return ISBN-10 with space separators when passing variant 10 and space separators as argument', () => {
+          const isbn = faker.commerce.isbn({ variant: 10, separator: ' ' });
+
+          expect(
+            isbn,
+            'The expected match should be ISBN-10 with space separators'
+          ).toMatch(/^[01] [\d ]{9} [\dX]$/);
+        });
+
+        it('should return ISBN-13 with space separators when passing space separators as argument', () => {
+          const isbn = faker.commerce.isbn({ separator: ' ' });
+
+          expect(
+            isbn,
+            'The expected match should be ISBN-13 with space separators'
+          ).toMatch(/^978 [01] [\d ]{9} \d$/);
+        });
+      });
     }
   );
 });

From f0c96b761b790a576d358c5e959bc29eacbe0037 Mon Sep 17 00:00:00 2001
From: Robin van der Vliet <info@robinvandervliet.com>
Date: Thu, 6 Jul 2023 00:55:44 +0200
Subject: [PATCH 03/11] Improve variable names

---
 src/modules/commerce/index.ts | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/modules/commerce/index.ts b/src/modules/commerce/index.ts
index 6e9403e8aae..7b60851ebc5 100644
--- a/src/modules/commerce/index.ts
+++ b/src/modules/commerce/index.ts
@@ -2,7 +2,9 @@ import type { Faker } from '../../faker';
 import { deprecated } from '../../internal/deprecated';
 
 // Source for official prefixes: https://www.isbn-international.org/range_file_generation
-const ISBN_LENGTH_RULES: { [key: string]: Array<[number, number]> } = {
+const ISBN_LENGTH_RULES: {
+  [group: string]: Array<[rangeMaximum: number, length: number]>;
+} = {
   '0': [
     [1999999, 2],
     [2279999, 3],
@@ -388,7 +390,8 @@ export class CommerceModule {
     const element: string = this.faker.string.numeric(8);
 
     const registrantLength: number = ISBN_LENGTH_RULES[group].find(
-      ([key]): boolean => parseInt(element.slice(0, -1)) <= key
+      ([rangeMaximum]): boolean =>
+        parseInt(element.slice(0, -1)) <= rangeMaximum
     )[1];
 
     const registrant: string = element.slice(0, registrantLength);

From 20a8d6b6d7b19ecdcb5187b4c0a3bafbca75bfcd Mon Sep 17 00:00:00 2001
From: Robin van der Vliet <info@robinvandervliet.com>
Date: Thu, 6 Jul 2023 18:54:28 +0200
Subject: [PATCH 04/11] Add tests for ISBN method

---
 test/__snapshots__/commerce.spec.ts.snap | 48 ++++++++++++++++++++++++
 test/commerce.spec.ts                    | 11 ++++++
 2 files changed, 59 insertions(+)

diff --git a/test/__snapshots__/commerce.spec.ts.snap b/test/__snapshots__/commerce.spec.ts.snap
index 1dde678565e..7844fb4d8ef 100644
--- a/test/__snapshots__/commerce.spec.ts.snap
+++ b/test/__snapshots__/commerce.spec.ts.snap
@@ -2,6 +2,22 @@
 
 exports[`commerce > 42 > department 1`] = `"Tools"`;
 
+exports[`commerce > 42 > isbn > noArgs 1`] = `"978-0-7917-7551-6"`;
+
+exports[`commerce > 42 > isbn > with space separator 1`] = `"978 0 7917 7551 6"`;
+
+exports[`commerce > 42 > isbn > with space separators 1`] = `"978 0 7917 7551 6"`;
+
+exports[`commerce > 42 > isbn > with variant 10 1`] = `"0-7917-7551-8"`;
+
+exports[`commerce > 42 > isbn > with variant 10 and space separator 1`] = `"0 7917 7551 8"`;
+
+exports[`commerce > 42 > isbn > with variant 10 and space separators 1`] = `"0 7917 7551 8"`;
+
+exports[`commerce > 42 > isbn > with variant 13 1`] = `"978-0-7917-7551-6"`;
+
+exports[`commerce > 42 > isbn 1`] = `"978-0-7917-7551-6"`;
+
 exports[`commerce > 42 > price > noArgs 1`] = `"375.00"`;
 
 exports[`commerce > 42 > price > with max 1`] = `"375.00"`;
@@ -36,6 +52,22 @@ exports[`commerce > 42 > productName 1`] = `"Fantastic Soft Sausages"`;
 
 exports[`commerce > 1211 > department 1`] = `"Automotive"`;
 
+exports[`commerce > 1211 > isbn > noArgs 1`] = `"978-1-4872-1906-2"`;
+
+exports[`commerce > 1211 > isbn > with space separator 1`] = `"978 1 4872 1906 2"`;
+
+exports[`commerce > 1211 > isbn > with space separators 1`] = `"978 1 4872 1906 2"`;
+
+exports[`commerce > 1211 > isbn > with variant 10 1`] = `"1-4872-1906-7"`;
+
+exports[`commerce > 1211 > isbn > with variant 10 and space separator 1`] = `"1 4872 1906 7"`;
+
+exports[`commerce > 1211 > isbn > with variant 10 and space separators 1`] = `"1 4872 1906 7"`;
+
+exports[`commerce > 1211 > isbn > with variant 13 1`] = `"978-1-4872-1906-2"`;
+
+exports[`commerce > 1211 > isbn 1`] = `"978-1-4872-1906-2"`;
+
 exports[`commerce > 1211 > price > noArgs 1`] = `"929.00"`;
 
 exports[`commerce > 1211 > price > with max 1`] = `"929.00"`;
@@ -70,6 +102,22 @@ exports[`commerce > 1211 > productName 1`] = `"Unbranded Cotton Salad"`;
 
 exports[`commerce > 1337 > department 1`] = `"Computers"`;
 
+exports[`commerce > 1337 > isbn > noArgs 1`] = `"978-0-512-25403-0"`;
+
+exports[`commerce > 1337 > isbn > with space separator 1`] = `"978 0 512 25403 0"`;
+
+exports[`commerce > 1337 > isbn > with space separators 1`] = `"978 0 512 25403 0"`;
+
+exports[`commerce > 1337 > isbn > with variant 10 1`] = `"0-512-25403-6"`;
+
+exports[`commerce > 1337 > isbn > with variant 10 and space separator 1`] = `"0 512 25403 6"`;
+
+exports[`commerce > 1337 > isbn > with variant 10 and space separators 1`] = `"0 512 25403 6"`;
+
+exports[`commerce > 1337 > isbn > with variant 13 1`] = `"978-0-512-25403-0"`;
+
+exports[`commerce > 1337 > isbn 1`] = `"978-0-512-25403-0"`;
+
 exports[`commerce > 1337 > price > noArgs 1`] = `"263.00"`;
 
 exports[`commerce > 1337 > price > with max 1`] = `"263.00"`;
diff --git a/test/commerce.spec.ts b/test/commerce.spec.ts
index bd65b9be294..ee2ed5fa008 100644
--- a/test/commerce.spec.ts
+++ b/test/commerce.spec.ts
@@ -38,6 +38,17 @@ describe('commerce', () => {
           symbol: '$',
         });
     });
+
+    t.describe('isbn', (t) => {
+      t.it('noArgs')
+        .it('with variant 10', 10)
+        .it('with variant 13', 13)
+        .it('with variant 10 and space separators', {
+          variant: 10,
+          separator: ' ',
+        })
+        .it('with space separators', { separator: ' ' });
+    });
   });
 
   describe.each(times(NON_SEEDED_BASED_RUN).map(() => faker.seed()))(

From 3e75ef1c70b36887c0be5fcd0bcd2b203141fdc1 Mon Sep 17 00:00:00 2001
From: Robin van der Vliet <info@robinvandervliet.com>
Date: Thu, 6 Jul 2023 19:14:17 +0200
Subject: [PATCH 05/11] Update snap file

---
 test/__snapshots__/commerce.spec.ts.snap | 18 ------------------
 1 file changed, 18 deletions(-)

diff --git a/test/__snapshots__/commerce.spec.ts.snap b/test/__snapshots__/commerce.spec.ts.snap
index 7844fb4d8ef..00b8f08e58a 100644
--- a/test/__snapshots__/commerce.spec.ts.snap
+++ b/test/__snapshots__/commerce.spec.ts.snap
@@ -4,20 +4,14 @@ exports[`commerce > 42 > department 1`] = `"Tools"`;
 
 exports[`commerce > 42 > isbn > noArgs 1`] = `"978-0-7917-7551-6"`;
 
-exports[`commerce > 42 > isbn > with space separator 1`] = `"978 0 7917 7551 6"`;
-
 exports[`commerce > 42 > isbn > with space separators 1`] = `"978 0 7917 7551 6"`;
 
 exports[`commerce > 42 > isbn > with variant 10 1`] = `"0-7917-7551-8"`;
 
-exports[`commerce > 42 > isbn > with variant 10 and space separator 1`] = `"0 7917 7551 8"`;
-
 exports[`commerce > 42 > isbn > with variant 10 and space separators 1`] = `"0 7917 7551 8"`;
 
 exports[`commerce > 42 > isbn > with variant 13 1`] = `"978-0-7917-7551-6"`;
 
-exports[`commerce > 42 > isbn 1`] = `"978-0-7917-7551-6"`;
-
 exports[`commerce > 42 > price > noArgs 1`] = `"375.00"`;
 
 exports[`commerce > 42 > price > with max 1`] = `"375.00"`;
@@ -54,20 +48,14 @@ exports[`commerce > 1211 > department 1`] = `"Automotive"`;
 
 exports[`commerce > 1211 > isbn > noArgs 1`] = `"978-1-4872-1906-2"`;
 
-exports[`commerce > 1211 > isbn > with space separator 1`] = `"978 1 4872 1906 2"`;
-
 exports[`commerce > 1211 > isbn > with space separators 1`] = `"978 1 4872 1906 2"`;
 
 exports[`commerce > 1211 > isbn > with variant 10 1`] = `"1-4872-1906-7"`;
 
-exports[`commerce > 1211 > isbn > with variant 10 and space separator 1`] = `"1 4872 1906 7"`;
-
 exports[`commerce > 1211 > isbn > with variant 10 and space separators 1`] = `"1 4872 1906 7"`;
 
 exports[`commerce > 1211 > isbn > with variant 13 1`] = `"978-1-4872-1906-2"`;
 
-exports[`commerce > 1211 > isbn 1`] = `"978-1-4872-1906-2"`;
-
 exports[`commerce > 1211 > price > noArgs 1`] = `"929.00"`;
 
 exports[`commerce > 1211 > price > with max 1`] = `"929.00"`;
@@ -104,20 +92,14 @@ exports[`commerce > 1337 > department 1`] = `"Computers"`;
 
 exports[`commerce > 1337 > isbn > noArgs 1`] = `"978-0-512-25403-0"`;
 
-exports[`commerce > 1337 > isbn > with space separator 1`] = `"978 0 512 25403 0"`;
-
 exports[`commerce > 1337 > isbn > with space separators 1`] = `"978 0 512 25403 0"`;
 
 exports[`commerce > 1337 > isbn > with variant 10 1`] = `"0-512-25403-6"`;
 
-exports[`commerce > 1337 > isbn > with variant 10 and space separator 1`] = `"0 512 25403 6"`;
-
 exports[`commerce > 1337 > isbn > with variant 10 and space separators 1`] = `"0 512 25403 6"`;
 
 exports[`commerce > 1337 > isbn > with variant 13 1`] = `"978-0-512-25403-0"`;
 
-exports[`commerce > 1337 > isbn 1`] = `"978-0-512-25403-0"`;
-
 exports[`commerce > 1337 > price > noArgs 1`] = `"263.00"`;
 
 exports[`commerce > 1337 > price > with max 1`] = `"263.00"`;

From d48b747de66cfe1ec9522e098fcbacd4f1a175f3 Mon Sep 17 00:00:00 2001
From: Robin van der Vliet <info@robinvandervliet.com>
Date: Sun, 9 Jul 2023 12:38:59 +0200
Subject: [PATCH 06/11] Use `helpers.objectKey` instead of `number.int`

---
 src/modules/commerce/index.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/modules/commerce/index.ts b/src/modules/commerce/index.ts
index 7b60851ebc5..b4b1816c150 100644
--- a/src/modules/commerce/index.ts
+++ b/src/modules/commerce/index.ts
@@ -386,7 +386,9 @@ export class CommerceModule {
     const { variant = 13, separator = '-' } = options;
 
     const prefix = '978';
-    const group: string = this.faker.number.int({ min: 0, max: 1 }).toString();
+    const group: string = this.faker.helpers
+      .objectKey(ISBN_LENGTH_RULES)
+      .toString();
     const element: string = this.faker.string.numeric(8);
 
     const registrantLength: number = ISBN_LENGTH_RULES[group].find(

From 2b3ab5e7f38d49042375a427c57ca13f05c51e88 Mon Sep 17 00:00:00 2001
From: Robin van der Vliet <info@robinvandervliet.com>
Date: Sun, 9 Jul 2023 12:39:25 +0200
Subject: [PATCH 07/11] Remove obvious explicit type definition

---
 src/modules/commerce/index.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/modules/commerce/index.ts b/src/modules/commerce/index.ts
index b4b1816c150..fe3c184f04c 100644
--- a/src/modules/commerce/index.ts
+++ b/src/modules/commerce/index.ts
@@ -408,7 +408,7 @@ export class CommerceModule {
 
     let checksum = 0;
     for (let i = 0; i < variant - 1; i++) {
-      const weight: number = variant === 10 ? i + 1 : i % 2 ? 3 : 1;
+      const weight = variant === 10 ? i + 1 : i % 2 ? 3 : 1;
       checksum += weight * parseInt(isbn[i]);
     }
 

From f605d3aeea40aee52bf8cedddafc720f6402948a Mon Sep 17 00:00:00 2001
From: Robin van der Vliet <info@robinvandervliet.com>
Date: Sun, 9 Jul 2023 12:41:38 +0200
Subject: [PATCH 08/11] Validate ISBN with validator.js

---
 test/commerce.spec.ts | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/test/commerce.spec.ts b/test/commerce.spec.ts
index ee2ed5fa008..b8422b65a5a 100644
--- a/test/commerce.spec.ts
+++ b/test/commerce.spec.ts
@@ -1,3 +1,4 @@
+import validator from 'validator';
 import { describe, expect, it } from 'vitest';
 import { faker } from '../src';
 import { seededTests } from './support/seededRuns';
@@ -180,6 +181,7 @@ describe('commerce', () => {
             isbn,
             'The expected match should be ISBN-13 with hyphens'
           ).toMatch(/^978-[01]-[\d-]{9}-\d$/);
+          expect(isbn).toSatisfy((isbn: string) => validator.isISBN(isbn, 13));
         });
 
         it('should return ISBN-10 with hyphen separators when passing variant 10 as argument', () => {
@@ -189,6 +191,7 @@ describe('commerce', () => {
             isbn,
             'The expected match should be ISBN-10 with hyphens'
           ).toMatch(/^[01]-[\d-]{9}-[\dX]$/);
+          expect(isbn).toSatisfy((isbn: string) => validator.isISBN(isbn, 10));
         });
 
         it('should return ISBN-13 with hyphen separators when passing variant 13 as argument', () => {
@@ -198,6 +201,7 @@ describe('commerce', () => {
             isbn,
             'The expected match should be ISBN-13 with hyphens'
           ).toMatch(/^978-[01]-[\d-]{9}-\d$/);
+          expect(isbn).toSatisfy((isbn: string) => validator.isISBN(isbn, 13));
         });
 
         it('should return ISBN-10 with space separators when passing variant 10 and space separators as argument', () => {
@@ -207,6 +211,7 @@ describe('commerce', () => {
             isbn,
             'The expected match should be ISBN-10 with space separators'
           ).toMatch(/^[01] [\d ]{9} [\dX]$/);
+          expect(isbn).toSatisfy((isbn: string) => validator.isISBN(isbn, 10));
         });
 
         it('should return ISBN-13 with space separators when passing space separators as argument', () => {
@@ -216,6 +221,7 @@ describe('commerce', () => {
             isbn,
             'The expected match should be ISBN-13 with space separators'
           ).toMatch(/^978 [01] [\d ]{9} \d$/);
+          expect(isbn).toSatisfy((isbn: string) => validator.isISBN(isbn, 13));
         });
       });
     }

From 84f30baa7b978c9e64ce667d49b21f8e0a3a5a04 Mon Sep 17 00:00:00 2001
From: Robin van der Vliet <info@robinvandervliet.com>
Date: Thu, 20 Jul 2023 19:32:19 +0200
Subject: [PATCH 09/11] Remove explicit type defintions

---
 src/modules/commerce/index.ts | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/src/modules/commerce/index.ts b/src/modules/commerce/index.ts
index fe3c184f04c..bcc561611da 100644
--- a/src/modules/commerce/index.ts
+++ b/src/modules/commerce/index.ts
@@ -386,25 +386,22 @@ export class CommerceModule {
     const { variant = 13, separator = '-' } = options;
 
     const prefix = '978';
-    const group: string = this.faker.helpers
-      .objectKey(ISBN_LENGTH_RULES)
-      .toString();
-    const element: string = this.faker.string.numeric(8);
+    const group = this.faker.helpers.objectKey(ISBN_LENGTH_RULES).toString();
+    const element = this.faker.string.numeric(8);
 
-    const registrantLength: number = ISBN_LENGTH_RULES[group].find(
-      ([rangeMaximum]): boolean =>
-        parseInt(element.slice(0, -1)) <= rangeMaximum
+    const registrantLength = ISBN_LENGTH_RULES[group].find(
+      ([rangeMaximum]) => parseInt(element.slice(0, -1)) <= rangeMaximum
     )[1];
 
-    const registrant: string = element.slice(0, registrantLength);
-    const publication: string = element.slice(registrantLength);
+    const registrant = element.slice(0, registrantLength);
+    const publication = element.slice(registrantLength);
 
-    const data: string[] = [prefix, group, registrant, publication];
+    const data = [prefix, group, registrant, publication];
     if (variant === 10) {
       data.shift();
     }
 
-    const isbn: string = data.join('');
+    const isbn = data.join('');
 
     let checksum = 0;
     for (let i = 0; i < variant - 1; i++) {

From 02a55ab571ed88808ba2e28eddc006b921e2f1c7 Mon Sep 17 00:00:00 2001
From: Robin van der Vliet <info@robinvandervliet.com>
Date: Thu, 20 Jul 2023 19:33:47 +0200
Subject: [PATCH 10/11] Simplify group rule selection

---
 src/modules/commerce/index.ts | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/modules/commerce/index.ts b/src/modules/commerce/index.ts
index bcc561611da..318e6a45c27 100644
--- a/src/modules/commerce/index.ts
+++ b/src/modules/commerce/index.ts
@@ -2,9 +2,10 @@ import type { Faker } from '../../faker';
 import { deprecated } from '../../internal/deprecated';
 
 // Source for official prefixes: https://www.isbn-international.org/range_file_generation
-const ISBN_LENGTH_RULES: {
-  [group: string]: Array<[rangeMaximum: number, length: number]>;
-} = {
+const ISBN_LENGTH_RULES: Record<
+  string,
+  Array<[rangeMaximum: number, length: number]>
+> = {
   '0': [
     [1999999, 2],
     [2279999, 3],
@@ -386,11 +387,13 @@ export class CommerceModule {
     const { variant = 13, separator = '-' } = options;
 
     const prefix = '978';
-    const group = this.faker.helpers.objectKey(ISBN_LENGTH_RULES).toString();
+    const [group, groupRules] =
+      this.faker.helpers.objectEntry(ISBN_LENGTH_RULES);
     const element = this.faker.string.numeric(8);
+    const elementValue = parseInt(element.slice(0, -1));
 
-    const registrantLength = ISBN_LENGTH_RULES[group].find(
-      ([rangeMaximum]) => parseInt(element.slice(0, -1)) <= rangeMaximum
+    const registrantLength = groupRules.find(
+      ([rangeMaximum]) => elementValue <= rangeMaximum
     )[1];
 
     const registrant = element.slice(0, registrantLength);

From 2a6552f5da57c5ae6e8180527b5cc4afbe84a257 Mon Sep 17 00:00:00 2001
From: Robin van der Vliet <info@robinvandervliet.com>
Date: Thu, 20 Jul 2023 22:49:46 +0200
Subject: [PATCH 11/11] Update `@since`

Co-authored-by: ST-DDT <ST-DDT@gmx.de>
---
 src/modules/commerce/index.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/modules/commerce/index.ts b/src/modules/commerce/index.ts
index 96c46a3f4c4..2464af03020 100644
--- a/src/modules/commerce/index.ts
+++ b/src/modules/commerce/index.ts
@@ -348,7 +348,7 @@ export class CommerceModule {
    * faker.commerce.isbn({ variant: 10, separator: ' ' }) // '0 940319 49 7'
    * faker.commerce.isbn({ variant: 13, separator: ' ' }) // '978 1 6618 9122 0'
    *
-   * @since 8.0.0
+   * @since 8.1.0
    */
   isbn(
     options: