feat: add getAcceptLanguage

README.md

@@ -132,6 +132,7 @@ You can do `import { ... } from '@intlify/utils'` the above utilities
 ### HTTP
 
 - `getAcceptLanguages`
+- `getAcceptLanguage`
 - `getLocale`
 - `getCookieLocale`
 - `setCookieLocale`

src/h3.test.ts

@@ -2,6 +2,7 @@ import { beforeEach, describe, expect, test } from 'vitest'
 import { createApp, eventHandler, toNodeListener } from 'h3'
 import supertest from 'supertest'
 import {
+  getAcceptLanguage,
   getAcceptLanguages,
   getCookieLocale,
   getLocale,
@@ -14,7 +15,7 @@ import type { SuperTest, Test } from 'supertest'
 
 describe('getAcceptLanguages', () => {
   test('basic', () => {
-    const eventMock = {
+    const mockEvent = {
       node: {
         req: {
           method: 'GET',
@@ -24,11 +25,11 @@ describe('getAcceptLanguages', () => {
         },
       },
     } as H3Event
-    expect(getAcceptLanguages(eventMock)).toEqual(['en-US', 'en', 'ja'])
+    expect(getAcceptLanguages(mockEvent)).toEqual(['en-US', 'en', 'ja'])
   })
 
   test('any language', () => {
-    const eventMock = {
+    const mockEvent = {
       node: {
         req: {
           method: 'GET',
@@ -38,25 +39,67 @@ describe('getAcceptLanguages', () => {
         },
       },
     } as H3Event
-    expect(getAcceptLanguages(eventMock)).toEqual([])
+    expect(getAcceptLanguages(mockEvent)).toEqual([])
   })
 
   test('empty', () => {
-    const eventMock = {
+    const mockEvent = {
       node: {
         req: {
           method: 'GET',
           headers: {},
         },
       },
     } as H3Event
-    expect(getAcceptLanguages(eventMock)).toEqual([])
+    expect(getAcceptLanguages(mockEvent)).toEqual([])
+  })
+})
+
+describe('getAcceptLanguage', () => {
+  test('basic', () => {
+    const mockEvent = {
+      node: {
+        req: {
+          method: 'GET',
+          headers: {
+            'accept-language': 'en-US,en;q=0.9,ja;q=0.8',
+          },
+        },
+      },
+    } as H3Event
+    expect(getAcceptLanguage(mockEvent)).toEqual('en-US')
+  })
+
+  test('any language', () => {
+    const mockEvent = {
+      node: {
+        req: {
+          method: 'GET',
+          headers: {
+            'accept-language': '*',
+          },
+        },
+      },
+    } as H3Event
+    expect(getAcceptLanguage(mockEvent)).toEqual('')
+  })
+
+  test('empty', () => {
+    const mockEvent = {
+      node: {
+        req: {
+          method: 'GET',
+          headers: {},
+        },
+      },
+    } as H3Event
+    expect(getAcceptLanguage(mockEvent)).toEqual('')
   })
 })
 
 describe('getLocale', () => {
   test('basic', () => {
-    const eventMock = {
+    const mockEvent = {
       node: {
         req: {
           method: 'GET',
@@ -66,15 +109,15 @@ describe('getLocale', () => {
         },
       },
     } as H3Event
-    const locale = getLocale(eventMock)
+    const locale = getLocale(mockEvent)
 
     expect(locale.baseName).toEqual('en-US')
     expect(locale.language).toEqual('en')
     expect(locale.region).toEqual('US')
   })
 
   test('accept-language is any language', () => {
-    const eventMock = {
+    const mockEvent = {
       node: {
         req: {
           method: 'GET',
@@ -84,13 +127,13 @@ describe('getLocale', () => {
         },
       },
     } as H3Event
-    const locale = getLocale(eventMock)
+    const locale = getLocale(mockEvent)
 
     expect(locale.baseName).toEqual(DEFAULT_LANG_TAG)
   })
 
   test('specify default language', () => {
-    const eventMock = {
+    const mockEvent = {
       node: {
         req: {
           method: 'GET',
@@ -100,13 +143,13 @@ describe('getLocale', () => {
         },
       },
     } as H3Event
-    const locale = getLocale(eventMock, 'ja-JP')
+    const locale = getLocale(mockEvent, 'ja-JP')
 
     expect(locale.baseName).toEqual('ja-JP')
   })
 
   test('RangeError', () => {
-    const eventMock = {
+    const mockEvent = {
       node: {
         req: {
           method: 'GET',
@@ -117,13 +160,13 @@ describe('getLocale', () => {
       },
     } as H3Event
 
-    expect(() => getLocale(eventMock, 'ja-JP')).toThrowError(RangeError)
+    expect(() => getLocale(mockEvent, 'ja-JP')).toThrowError(RangeError)
   })
 })
 
 describe('getCookieLocale', () => {
   test('basic', () => {
-    const eventMock = {
+    const mockEvent = {
       node: {
         req: {
           method: 'GET',
@@ -133,43 +176,43 @@ describe('getCookieLocale', () => {
         },
       },
     } as H3Event
-    const locale = getCookieLocale(eventMock)
+    const locale = getCookieLocale(mockEvent)
 
     expect(locale.baseName).toEqual('ja-US')
     expect(locale.language).toEqual('ja')
     expect(locale.region).toEqual('US')
   })
 
   test('cookie is empty', () => {
-    const eventMock = {
+    const mockEvent = {
       node: {
         req: {
           method: 'GET',
           headers: {},
         },
       },
     } as H3Event
-    const locale = getCookieLocale(eventMock)
+    const locale = getCookieLocale(mockEvent)
 
     expect(locale.baseName).toEqual(DEFAULT_LANG_TAG)
   })
 
   test('specify default language', () => {
-    const eventMock = {
+    const mockEvent = {
       node: {
         req: {
           method: 'GET',
           headers: {},
         },
       },
     } as H3Event
-    const locale = getCookieLocale(eventMock, { lang: 'ja-JP' })
+    const locale = getCookieLocale(mockEvent, { lang: 'ja-JP' })
 
     expect(locale.baseName).toEqual('ja-JP')
   })
 
   test('specify cookie name', () => {
-    const eventMock = {
+    const mockEvent = {
       node: {
         req: {
           method: 'GET',
@@ -179,13 +222,13 @@ describe('getCookieLocale', () => {
         },
       },
     } as H3Event
-    const locale = getCookieLocale(eventMock, { name: 'intlify_locale' })
+    const locale = getCookieLocale(mockEvent, { name: 'intlify_locale' })
 
     expect(locale.baseName).toEqual('fr-FR')
   })
 
   test('RangeError', () => {
-    const eventMock = {
+    const mockEvent = {
       node: {
         req: {
           method: 'GET',
@@ -196,7 +239,7 @@ describe('getCookieLocale', () => {
       },
     } as H3Event
 
-    expect(() => getCookieLocale(eventMock, { name: 'intlify_locale' }))
+    expect(() => getCookieLocale(mockEvent, { name: 'intlify_locale' }))
       .toThrowError(RangeError)
   })
 })

src/h3.ts

@@ -40,6 +40,17 @@ export function getAcceptLanguages(event: H3Event): string[] {
   return getAcceptLanguagesWithGetter(getter)
 }
 
+/**
+ * get accept language
+ *
+ * @param {H3Event} event The {@link H3Event | H3} event
+ *
+ * @returns {string} The **first language tag** of `accept-language` header, if `accept-language` header is not exists, or `*` (any language), return empty string.
+ */
+export function getAcceptLanguage(event: H3Event): string {
+  return getAcceptLanguages(event)[0] || ''
+}
+
 /**
  * get locale
  *

src/node.test.ts

@@ -1,6 +1,7 @@
 import { describe, expect, test } from 'vitest'
 import supertest from 'supertest'
 import {
+  getAcceptLanguage,
   getAcceptLanguages,
   getCookieLocale,
   getLocale,
@@ -36,6 +37,33 @@ describe('getAcceptLanguages', () => {
   })
 })
 
+describe('getAcceptLanguage', () => {
+  test('basic', () => {
+    const mockRequest = {
+      headers: {
+        'accept-language': 'en-US,en;q=0.9,ja;q=0.8',
+      },
+    } as IncomingMessage
+    expect(getAcceptLanguage(mockRequest)).toBe('en-US')
+  })
+
+  test('any language', () => {
+    const mockRequest = {
+      headers: {
+        'accept-language': '*',
+      },
+    } as IncomingMessage
+    expect(getAcceptLanguage(mockRequest)).toBe('')
+  })
+
+  test('empty', () => {
+    const mockRequest = {
+      headers: {},
+    } as IncomingMessage
+    expect(getAcceptLanguage(mockRequest)).toBe('')
+  })
+})
+
 describe('getLocale', () => {
   test('basic', () => {
     const mockRequest = {

src/node.ts

@@ -32,11 +32,22 @@ import type { CookieOptions } from './http.ts'
  *
  * @returns {Array<string>} The array of language tags, if `*` (any language) or empty string is detected, return an empty array.
  */
-export function getAcceptLanguages(req: IncomingMessage) {
+export function getAcceptLanguages(req: IncomingMessage): string[] {
   const getter = () => req.headers['accept-language']
   return getAcceptLanguagesWithGetter(getter)
 }
 
+/**
+ * get accept language
+ *
+ * @param {IncomingMessage} request The {@link IncomingMessage | request}
+ *
+ * @returns {string} The **first language tag** of `accept-language` header, if `accept-language` header is not exists, or `*` (any language), return empty string.
+ */
+export function getAcceptLanguage(req: IncomingMessage): string {
+  return getAcceptLanguages(req)[0] || ''
+}
+
 /**
  * get locale
  *

src/web.test.ts

@@ -1,5 +1,6 @@
 import { describe, expect, test } from 'vitest'
 import {
+  getAcceptLanguage,
   getAcceptLanguages,
   getCookieLocale,
   getLocale,
@@ -26,6 +27,25 @@ describe('getAcceptLanguages', () => {
   })
 })
 
+describe('getAcceptLanguage', () => {
+  test('basic', () => {
+    const mockRequest = new Request('https://example.com')
+    mockRequest.headers.set('accept-language', 'en-US,en;q=0.9,ja;q=0.8')
+    expect(getAcceptLanguage(mockRequest)).toBe('en-US')
+  })
+
+  test('any language', () => {
+    const mockRequest = new Request('https://example.com')
+    mockRequest.headers.set('accept-language', '*')
+    expect(getAcceptLanguage(mockRequest)).toBe('')
+  })
+
+  test('empty', () => {
+    const mockRequest = new Request('https://example.com')
+    expect(getAcceptLanguage(mockRequest)).toBe('')
+  })
+})
+
 describe('getLocale', () => {
   test('basic', () => {
     const mockRequest = new Request('https://example.com')

src/web.ts

@@ -33,11 +33,22 @@ import type { CookieOptions } from './http.ts'
  *
  * @returns {Array<string>} The array of language tags, if `*` (any language) or empty string is detected, return an empty array.
  */
-export function getAcceptLanguages(req: Request) {
+export function getAcceptLanguages(req: Request): string[] {
   const getter = () => req.headers.get('accept-language')
   return getAcceptLanguagesWithGetter(getter)
 }
 
+/**
+ * get accept language
+ *
+ * @param {Request} request The {@link Request | request}
+ *
+ * @returns {string} The **first language tag** of `accept-language` header, if `accept-language` header is not exists, or `*` (any language), return empty string.
+ */
+export function getAcceptLanguage(req: Request): string {
+  return getAcceptLanguages(req)[0] || ''
+}
+
 /**
  * get locale
  *