feat: add parseAcceptLanguage (#2)

deno/mod.ts

@@ -1 +1,2 @@
+// TODO: we must change package structure for deno
 export * from '../src/index.ts'

mod.ts

@@ -0,0 +1,3 @@
+import { isLocale } from 'https://deno.land/x/intlify_utils'
+
+console.log('isLocale', isLocale(new Intl.Locale('en-US')))

src/index.ts

@@ -11,3 +11,16 @@ const toTypeString = (value: unknown): string => objectToString.call(value)
 export function isLocale(val: unknown): val is Intl.Locale {
   return toTypeString(val) === '[object Intl.Locale]'
 }
+
+/**
+ * parse `accept-language` header string
+ *
+ * @param {string} value The accept-language header string
+ *
+ * @returns {Array<string>} The array of language tags, if `*` (any language) or empty string is detected, return an empty array.
+ */
+export function parseAcceptLanguage(value: string): string[] {
+  return value.split(',').map((tag) => tag.split(';')[0]).filter((tag) =>
+    !(tag === '*' || tag === '')
+  )
+}

test/index.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, test } from 'vitest'
-import { isLocale } from '../src/index.ts'
+import { isLocale, parseAcceptLanguage } from '../src/index.ts'
 
 describe('isLocale', () => {
   test('Locale instance', () => {
@@ -10,3 +10,34 @@ describe('isLocale', () => {
     expect(isLocale('en-US')).toBe(false)
   })
 })
+
+describe('parseAcceptLanguage', () => {
+  test('basic: ja,en-US;q=0.7,en;q=0.3', () => {
+    expect(parseAcceptLanguage('ja,en-US;q=0.7,en;q=0.3')).toEqual([
+      'ja',
+      'en-US',
+      'en',
+    ])
+  })
+
+  test('q-factor nothing: ja,en-US', () => {
+    expect(parseAcceptLanguage('ja,en-US')).toEqual([
+      'ja',
+      'en-US',
+    ])
+  })
+
+  test('single: ja', () => {
+    expect(parseAcceptLanguage('ja')).toEqual([
+      'ja',
+    ])
+  })
+
+  test('any language: *', () => {
+    expect(parseAcceptLanguage('*')).toEqual([])
+  })
+
+  test('empty: ""', () => {
+    expect(parseAcceptLanguage('')).toEqual([])
+  })
+})