feat(theme): allow forcing site locale in last updated format (#2973)

docs/reference/default-theme-config.md

@@ -331,7 +331,7 @@ export interface LastUpdatedOptions {
    * @default
    * { dateStyle: 'short',  timeStyle: 'short' }
    */
-  formatOptions?: Intl.DateTimeFormatOptions
+  formatOptions?: Intl.DateTimeFormatOptions & { forceLocale?: boolean }
 }
 ```
 

src/client/theme-default/components/VPDocFooterLastUpdated.vue

@@ -2,7 +2,7 @@
 import { ref, computed, watchEffect, onMounted } from 'vue'
 import { useData } from '../composables/data'
 
-const { theme, page, frontmatter } = useData()
+const { theme, page, frontmatter, lang } = useData()
 
 const date = computed(
   () => new Date(frontmatter.value.lastUpdated ?? page.value.lastUpdated)
@@ -15,7 +15,7 @@ const datetime = ref('')
 onMounted(() => {
   watchEffect(() => {
     datetime.value = new Intl.DateTimeFormat(
-      undefined,
+      theme.value.lastUpdated?.formatOptions?.forceLocale ? lang.value : undefined,
       theme.value.lastUpdated?.formatOptions ?? {
         dateStyle: 'short',
         timeStyle: 'short'

types/default-theme.d.ts

@@ -435,7 +435,7 @@ export namespace DefaultTheme {
      * @default
      * { dateStyle: 'short', timeStyle: 'short' }
      */
-    formatOptions?: Intl.DateTimeFormatOptions
+    formatOptions?: Intl.DateTimeFormatOptions & { forceLocale?: boolean }
   }
 
   // not found -----------------------------------------------------------------