feat(isISO6391): add ISO 639-1 validator (#1892)

* docs: add ISO 639-1 to readme

* feat: implement ISO 639-1 validator and test

* update readme

* fix: clean up whitespace in locale list

* refactor: write more concise test code

Author: braaar

README.md

@@ -130,6 +130,7 @@ Validator                               | Description
 **isIPRange(str [, version])**          | check if the string is an IP Range (version 4 or 6).
 **isISBN(str [, version])**             | check if the string is an ISBN (version 10 or 13).
 **isISIN(str)**                         | check if the string is an [ISIN][ISIN] (stock/security identifier).
+**isISO6391(str)**                      | check if the string is a valid [ISO 639-1](https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes) language code.
 **isISO8601(str [, options])**          | check if the string is a valid [ISO 8601](https://en.wikipedia.org/wiki/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.
 **isISO31661Alpha2(str)**               | check if the string is a valid [ISO 3166-1 alpha-2](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2) officially assigned country code.
 **isISO31661Alpha3(str)**               | check if the string is a valid [ISO 3166-1 alpha-3](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-3) officially assigned country code.

src/index.js

@@ -86,6 +86,7 @@ import isCurrency from './lib/isCurrency';
 
 import isBtcAddress from './lib/isBtcAddress';
 
+import isISO6391 from './lib/isISO6391';
 import isISO8601 from './lib/isISO8601';
 import isRFC3339 from './lib/isRFC3339';
 import isISO31661Alpha2 from './lib/isISO31661Alpha2';
@@ -195,6 +196,7 @@ const validator = {
   isEthereumAddress,
   isCurrency,
   isBtcAddress,
+  isISO6391,
   isISO8601,
   isRFC3339,
   isISO31661Alpha2,

src/lib/isISO6391.js

@@ -0,0 +1,35 @@
+import assertString from './util/assertString';
+
+const isISO6391Set = new Set([
+  'aa', 'ab', 'ae', 'af', 'ak', 'am', 'an', 'ar', 'as', 'av', 'ay', 'az', 'az',
+  'ba', 'be', 'bg', 'bh', 'bi', 'bm', 'bn', 'bo', 'br', 'bs',
+  'ca', 'ce', 'ch', 'co', 'cr', 'cs', 'cu', 'cv', 'cy',
+  'da', 'de', 'dv', 'dz',
+  'ee', 'el', 'en', 'eo', 'es', 'et', 'eu',
+  'fa', 'ff', 'fi', 'fj', 'fo', 'fr', 'fy',
+  'ga', 'gd', 'gl', 'gn', 'gu', 'gv',
+  'ha', 'he', 'hi', 'ho', 'hr', 'ht', 'hu', 'hy', 'hz',
+  'ia', 'id', 'ie', 'ig', 'ii', 'ik', 'io', 'is', 'it', 'iu',
+  'ja', 'jv',
+  'ka', 'kg', 'ki', 'kj', 'kk', 'kl', 'km', 'kn', 'ko', 'kr', 'ks', 'ku', 'kv', 'kw', 'ky',
+  'la', 'lb', 'lg', 'li', 'ln', 'lo', 'lt', 'lu', 'lv',
+  'mg', 'mh', 'mi', 'mk', 'ml', 'mn', 'mr', 'ms', 'mt', 'my',
+  'na', 'nb', 'nd', 'ne', 'ng', 'nl', 'nn', 'no', 'nr', 'nv', 'ny',
+  'oc', 'oj', 'om', 'or', 'os',
+  'pa', 'pi', 'pl', 'ps', 'pt',
+  'qu',
+  'rm', 'rn', 'ro', 'ru', 'rw',
+  'sa', 'sc', 'sd', 'se', 'sg', 'si', 'sk', 'sl', 'sm', 'sn', 'so', 'sq', 'sr', 'ss', 'st', 'su', 'sv', 'sw',
+  'ta', 'te', 'tg', 'th', 'ti', 'tk', 'tl', 'tn', 'to', 'tr', 'ts', 'tt', 'tw', 'ty',
+  'ug', 'uk', 'ur', 'uz',
+  've', 'vi', 'vo',
+  'wa', 'wo',
+  'xh',
+  'yi', 'yo',
+  'za', 'zh', 'zu',
+]);
+
+export default function isISO6391(str) {
+  assertString(str);
+  return isISO6391Set.has(str);
+}

test/validators.js

@@ -9792,6 +9792,14 @@ describe('Validators', () => {
     });
   });
 
+  it('should validate ISO 639-1 language codes', () => {
+    test({
+      validator: 'isISO6391',
+      valid: ['ay', 'az', 'ba', 'be', 'bg'],
+      invalid: ['aj', 'al', 'pe', 'pf', 'abc', '123', ''],
+    });
+  });
+
   const validISO8601 = [
     '2009-12T12:34',
     '2009',