Date region fallback support

Author: dragonstyle

news/changelog-1.3.md

@@ -4,6 +4,10 @@
 
 - Improve the performance of extremely large documents with margin elements by improving the efficiency of positioning the elements.
 
+## Dates
+
+- Properly fall back to language only locale when a supported language-region locale isn't available. (#3059)
+
 ## About Pages
 
 - Add support for `image-alt` which provides alternate text for the about page image. (#3010)

src/core/date.ts

@@ -135,17 +135,37 @@ export function initDayJsPlugins() {
   dayjs.extend(advancedPlugin);
 }
 
-export async function setDateLocale(locale: string) {
-  locale = locale.toLowerCase();
-  if (locale !== dayjs.locale()) {
-    const localePath = resourcePath(
-      `library/dayjs/locale/${locale}.js`,
-    );
-    if (existsSync(localePath)) {
-      const localeUrl = toFileUrl(localePath).href;
+export async function setDateLocale(localeStr: string) {
+  localeStr = localeStr.toLowerCase();
+  if (localeStr !== dayjs.locale()) {
+    // Try to find the language + region (e.g. fr-CA) first
+    // but fall back to just the language (e.g. fr)
+    const findLocale = () => {
+      const locales = [localeStr];
+      if (localeStr.includes("-")) {
+        locales.push(localeStr.split("-")[0]);
+      }
+
+      for (const locale of locales) {
+        const path = resourcePath(
+          `library/dayjs/locale/${locale}.js`,
+        );
+        if (existsSync(path)) {
+          return {
+            locale,
+            path,
+          };
+        }
+      }
+      return undefined;
+    };
+
+    const locale = findLocale();
+    if (locale) {
+      const localeUrl = toFileUrl(locale.path).href;
       const localeModule = await import(localeUrl);
       dayjs.locale(localeModule.default, null, true);
-      dayjs.locale(locale);
+      dayjs.locale(locale.locale);
     }
   }
 }

tests/docs/date/fr-CA.qmd

@@ -0,0 +1,7 @@
+---
+title: This is a Test
+date: 2022/10/1
+lang: fr-CA
+---
+
+## Hello Date!

tests/docs/date/fr-FR.qmd

@@ -0,0 +1,7 @@
+---
+title: This is a Test
+date: 2022/10/1
+lang: fr-FR
+---
+
+## Hello Date!

tests/docs/date/fr.qmd

@@ -0,0 +1,7 @@
+---
+title: This is a Test
+date: 2022/10/1
+lang: fr
+---
+
+## Hello Date!

tests/smoke/render/render-date.test.ts

@@ -11,14 +11,19 @@ import { testRender } from "./render.ts";
 const tests = [
   { input: docs("date/today.qmd"), noMatch: />today</ },
   { input: docs("date/lastmodified.qmd"), noMatch: />last-modified</ },
+  { input: docs("date/fr.qmd"), match: /octobre/, noMatch: /October/ },
+  { input: docs("date/fr-FR.qmd"), match: /octobre/, noMatch: /October/ },
+  { input: docs("date/fr-CA.qmd"), match: /octobre/, noMatch: /October/ },
 ];
 
 tests.forEach((test) => {
   const to = "html";
   const output = outputForInput(test.input, "html");
+
+  const noMatch = test.noMatch ? [test.noMatch] : [];
+  const match = test.match ? [test.match] : [];
+
   testRender(test.input, to, false, [
-    ensureFileRegexMatches(output.outputPath, [], [
-      test.noMatch,
-    ]),
+    ensureFileRegexMatches(output.outputPath, match, noMatch),
   ]);
 });