diff --git a/assets/js/preferred-lang/index.ts b/assets/js/preferred-lang/index.ts
new file mode 100644
index 00000000..c8f4737b
--- /dev/null
+++ b/assets/js/preferred-lang/index.ts
@@ -0,0 +1,23 @@
+import { default as params } from '@params';
+
+(() => {
+ const lang = navigator.language || navigator.userLanguage
+
+ // match the exact language code.
+ if (lang in params.homes) {
+ window.location.href = params.homes[lang]
+ return
+ }
+
+ // match the main language code.
+ const codes = lang.split('-')
+ for (let lang in params.homes) {
+ if (lang.indexOf(codes[0]) === 0) {
+ window.location.href = params.homes[lang]
+ return
+ }
+ }
+
+ // fallback to the default language.
+ window.location.href = params.fallback
+})()
diff --git a/layouts/alias.html b/layouts/alias.html
index 382852bb..ddb3dd2f 100644
--- a/layouts/alias.html
+++ b/layouts/alias.html
@@ -4,10 +4,24 @@
{{- partial "assets/init/js" .Page -}}
{{- partialCached "assets/main/css" .Page }}
+ {{- $isHome := eq .Permalink (site.Sites.First.Home.Permalink) }}
+ {{- if $isHome }}
+ {{- $homes := newScratch }}
+ {{- range site.Sites }}
+ {{- $homes.Set .Home.Lang .Home.Permalink }}
+ {{- end }}
+ {{- $opts := dict
+ "minify" hugo.IsProduction
+ "targetPath" "js/preferred-lang.js"
+ "params" (dict "homes" $homes.Values "fallback" .Permalink)
+ }}
+ {{- $js := resources.Get "js/preferred-lang/index.ts" | js.Build $opts }}
+
+ {{- end }}
{{ .Permalink }}
-
+