feat(isCurrency): add require_thousands_separator option

Add new option `require_thousands_separator` to enforce thousands separators
in currency values. When enabled, amounts of 1000 or greater must include
thousands separators (e.g., "1,234" is valid but "1234" is invalid).

This is useful for validating financial data where comma separators must
always be present.

Fixes #912

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: abhu85

README.md

@@ -100,7 +100,7 @@ Validator                               | Description
 **isBtcAddress(str)**            | check if the string is a valid BTC address.
 **isByteLength(str [, options])**          | check if the string's length (in UTF-8 bytes) falls in a range.<br/><br/>`options` is an object which defaults to `{ min: 0, max: undefined }`.
 **isCreditCard(str [, options])**                   | check if the string is a credit card number.<br/><br/> `options` is an optional object that can be supplied with the following key(s): `provider` is an optional key whose value should be a string, and defines the company issuing the credit card. Valid values include `['amex', 'dinersclub', 'discover', 'jcb', 'mastercard', 'unionpay', 'visa']` or blank will check for any provider.
-**isCurrency(str [, options])**            | check if the string is a valid currency amount.<br/><br/>`options` is an object which defaults to `{ symbol: '$', require_symbol: false, allow_space_after_symbol: false, symbol_after_digits: false, allow_negatives: true, parens_for_negatives: false, negative_sign_before_digits: false, negative_sign_after_digits: false, allow_negative_sign_placeholder: false, thousands_separator: ',', decimal_separator: '.', allow_decimal: true, require_decimal: false, digits_after_decimal: [2], allow_space_after_digits: false }`.<br/>**Note:** The array `digits_after_decimal` is filled with the exact number of digits allowed not a range, for example a range 1 to 3 will be given as [1, 2, 3].
+**isCurrency(str [, options])**            | check if the string is a valid currency amount.<br/><br/>`options` is an object which defaults to `{ symbol: '$', require_symbol: false, allow_space_after_symbol: false, symbol_after_digits: false, allow_negatives: true, parens_for_negatives: false, negative_sign_before_digits: false, negative_sign_after_digits: false, allow_negative_sign_placeholder: false, thousands_separator: ',', decimal_separator: '.', allow_decimal: true, require_decimal: false, digits_after_decimal: [2], allow_space_after_digits: false, require_thousands_separator: false }`.<br/>**Note:** The array `digits_after_decimal` is filled with the exact number of digits allowed not a range, for example a range 1 to 3 will be given as [1, 2, 3].
 **isDataURI(str)**                      | check if the string is a [data uri format][Data URI Format].
 **isDate(str [, options])**          | check if the string is a valid date. e.g. [`2002-07-15`, new Date()].<br/><br/> `options` is an object which can contain the keys `format`, `strictMode` and/or `delimiters`.<br/><br/>`format` is a string and defaults to `YYYY/MM/DD`.<br/><br/>`strictMode` is a boolean and defaults to `false`. If `strictMode` is set to true, the validator will reject strings different from `format`.<br/><br/> `delimiters` is an array of allowed date delimiters and defaults to `['/', '-']`.
 **isDecimal(str [, options])**             | check if the string represents a decimal number, such as 0.1, .3, 1.1, 1.00003, 4.0, etc.<br/><br/>`options` is an object which defaults to `{force_decimal: false, decimal_digits: '1,', locale: 'en-US'}`.<br/><br/>`locale` determines the decimal separator and is one of `['ar', 'ar-AE', 'ar-BH', 'ar-DZ', 'ar-EG', 'ar-IQ', 'ar-JO', 'ar-KW', 'ar-LB', 'ar-LY', 'ar-MA', 'ar-QA', 'ar-QM', 'ar-SA', 'ar-SD', 'ar-SY', 'ar-TN', 'ar-YE', 'bg-BG', 'cs-CZ', 'da-DK', 'de-DE', 'el-GR', 'en-AU', 'en-GB', 'en-HK', 'en-IN', 'en-NZ', 'en-US', 'en-ZA', 'en-ZM', 'eo', 'es-ES', 'fa', 'fa-AF', 'fa-IR', 'fr-FR', 'fr-CA', 'hu-HU', 'id-ID', 'it-IT', 'ku-IQ', 'nb-NO', 'nl-NL', 'nn-NO', 'pl-PL', 'pl-Pl', 'pt-BR', 'pt-PT', 'ru-RU', 'sl-SI', 'sr-RS', 'sr-RS@latin', 'sv-SE', 'tr-TR', 'uk-UA', 'vi-VN']`.<br/>**Note:** `decimal_digits` is given as a range like '1,3', a specific value like '3' or min like '1,'.

src/lib/isCurrency.js

@@ -10,8 +10,9 @@ function currencyRegex(options) {
     negative = '-?',
     whole_dollar_amount_without_sep = '[1-9]\\d*',
     whole_dollar_amount_with_sep = `[1-9]\\d{0,2}(\\${options.thousands_separator}\\d{3})*`,
-    valid_whole_dollar_amounts = [
-      '0', whole_dollar_amount_without_sep, whole_dollar_amount_with_sep],
+    valid_whole_dollar_amounts = options.require_thousands_separator
+      ? ['0', '[1-9]\\d{0,2}', whole_dollar_amount_with_sep]
+      : ['0', whole_dollar_amount_without_sep, whole_dollar_amount_with_sep],
     whole_dollar_amount = `(${valid_whole_dollar_amounts.join('|')})?`,
     decimal_amount = `(\\${options.decimal_separator}(${decimal_digits}))${options.require_decimal ? '' : '?'}`;
   let pattern = whole_dollar_amount + (options.allow_decimal || options.require_decimal ? decimal_amount : '');
@@ -70,6 +71,7 @@ const default_currency_options = {
   require_decimal: false,
   digits_after_decimal: [2],
   allow_space_after_digits: false,
+  require_thousands_separator: false,
 };
 
 export default function isCurrency(str, options) {

test/validators.test.js

@@ -12069,6 +12069,83 @@ describe('Validators', () => {
         '$R 1.400,00',
       ],
     });
+
+    // require_thousands_separator option (issue #912)
+    test({
+      validator: 'isCurrency',
+      args: [
+        {
+          require_thousands_separator: true,
+        },
+      ],
+      valid: [
+        '$10,123.45',
+        '-$10,123.45',
+        '$1,234.56',
+        '1,234.56',
+        '$1,234,567.89',
+        '1,234,567.89',
+        '$100.00',
+        '100.00',
+        '$10.00',
+        '10.00',
+        '$1.00',
+        '1.00',
+        '$0.50',
+        '0.50',
+        '.50',
+        '$.50',
+        '0',
+        '$0',
+        '999',
+        '$999',
+        '999.99',
+        '$999.99',
+      ],
+      invalid: [
+        '1234.56',
+        '$1234.56',
+        '1234',
+        '$1234',
+        '10000',
+        '$10000',
+        '1234567.89',
+        '$1234567.89',
+        '10000.00',
+        '$10000.00',
+      ],
+    });
+
+    // require_thousands_separator with different separator
+    test({
+      validator: 'isCurrency',
+      args: [
+        {
+          require_thousands_separator: true,
+          thousands_separator: '.',
+          decimal_separator: ',',
+          symbol: '€',
+          symbol_after_digits: true,
+        },
+      ],
+      valid: [
+        '10.123,45€',
+        '1.234,56€',
+        '1.234.567,89€',
+        '100,00€',
+        '10,00€',
+        '1,00€',
+        '0,50€',
+        '999€',
+        '999,99€',
+      ],
+      invalid: [
+        '1234,56€',
+        '1234€',
+        '10000€',
+        '1234567,89€',
+      ],
+    });
   });
 
   it('should validate Ethereum addresses', () => {