docs: fix accept-language handling

docs-site~/package.json

@@ -11,6 +11,6 @@
     "publish": "wrangler publish"
   },
   "dependencies": {
-    "accept-language": "^3.0.18"
+    "intl-parse-accept-language": "^1.0.0"
   }
 }

docs-site~/src/index.js

@@ -3,7 +3,7 @@ import {
   mapRequestToAsset,
 } from "@cloudflare/kv-asset-handler";
 
-import acceptLanguage from 'accept-language';
+import { parseAcceptLanguage } from 'intl-parse-accept-language';
 
 /**
  * The DEBUG flag will do two things that help during development:
@@ -20,8 +20,6 @@ addEventListener("fetch", (event) => {
 
 const STRIP_SUFFIX_RE = new RegExp('^(/.+)(?:/(?:index\.html)?|\.html)$');
 
-acceptLanguage.languages(['en-US', 'ja-JP']);
-
 async function handleEvent(event) {
   let options = {};
 
@@ -46,11 +44,21 @@ async function handleEvent(event) {
     const strip_match = STRIP_SUFFIX_RE.exec(path);
     
     if (url.searchParams.get("lang") === 'auto') {
-      let resolvedLanguage = acceptLanguage.get(event.request.headers.get('Accept-Language'));
-      if (resolvedLanguage === null) {
-        resolvedLanguage = 'en-US';
-      } else {
-        resolvedLanguage = resolvedLanguage.split('-')[0];
+      const languages = parseAcceptLanguage(event.request.headers.get('Accept-Language'));
+      
+      let resolvedLanguage = 'en';
+      if (languages !== null) {
+        for (const language of languages) {
+          if (language === 'ja' || language === 'ja-JP') {
+            resolvedLanguage = 'ja';
+            break;
+          }
+          
+          if (language === 'en' || language.startsWith('en-')) {
+            resolvedLanguage = 'en';
+            break;
+          }
+        }
       }
       
       let destination;

docs-site~/yarn.lock

@@ -978,6 +978,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"intl-parse-accept-language@npm:^1.0.0":
+  version: 1.0.0
+  resolution: "intl-parse-accept-language@npm:1.0.0"
+  checksum: c1dcc0f520cb85be391f1cf4b5f691ab19183e5d8e8f5277c0d2210a78a6d01ee907b9bb70f7425c4a8d5a9ed86f8b18a8d53f089025772d89f5cbe39282f266
+  languageName: node
+  linkType: hard
+
 "ip@npm:^2.0.0":
   version: 2.0.0
   resolution: "ip@npm:2.0.0"
@@ -1778,6 +1785,7 @@ __metadata:
   dependencies:
     "@cloudflare/kv-asset-handler": ^0.2.0
     accept-language: ^3.0.18
+    intl-parse-accept-language: ^1.0.0
     wrangler: ^3.11.0
   languageName: unknown
   linkType: soft