【Nuxt3】SSGでサイトマップを生成する【lastmod対応】

--- before.ts
+++ after.ts
@@ -1,32 +1,51 @@
 import type { Nitro } from "nitropack";
-import { SitemapStream, streamToPromise, SitemapItem } from 'sitemap';
+import { SitemapStream, streamToPromise, type SitemapItem } from 'sitemap';
 import { Readable } from 'stream';
-import { writeFileSync } from 'fs';
+import { readFileSync, writeFileSync } from 'fs';
+import { parse } from 'node-html-parser'
 import path from 'path';
+import { consola as logger } from 'consola';
+import { colors } from 'consola/utils';
 
 // サイトドメインを指定（最後スラッシュ不要）
-const domain = "https://YOUR_DOMAIN";
+const domain = process.env.BASE_URL || 'http://localhost:3000';
 
-export default async function genSitemap(nitro: Nitro) {
-    if (!nitro._prerenderedRoutes) {
-        return;
+export default async function generateSitemap(nitro: Nitro) {
+  if (!nitro._prerenderedRoutes) {
+    return;
+  }
+
+  logger.info("Generating Sitemap");
+  const startTime = process.hrtime();
+
+  const publicDir = nitro.options.output.publicDir;
+
+  const routes = nitro._prerenderedRoutes?.map((e) => e.fileName || null).filter((e, i, a) => e && a.indexOf(e) === i && e.endsWith("index.html")).map((e) => {
+    let lastmod = undefined
+
+    //ブログ記事ページの場合
+    if (e?.match(/^\/blog\/(?!tags\/)(?!index\.html$).*\.html$/)) {
+      const html = parse(readFileSync(path.join(publicDir, e), 'utf-8'))
+      const publishedTime = html.querySelector('meta[property="article:published_time"]')?.getAttribute('content')
+      const modifiedTime = html.querySelector('meta[property="article:modified_time"]')?.getAttribute('content')
+      lastmod = (modifiedTime || publishedTime)
     }
 
-    const publicDir = nitro.options.output.publicDir;
-
-    const routes = nitro._prerenderedRoutes?.map((e) => e.fileName || null).filter((e, i, a) => e && a.indexOf(e) === i && e.endsWith("index.html")).map((e) => {
-        return {
-            url: e?.replace(/index\.html$/, ''),
-       
-       // この辺の値は各自調整して下さい
-            changefreq: 'weekly',
-            priority: .7,
-        } as SitemapItem;
-    });
-    const smStream = new SitemapStream({ hostname: domain });
-    Readable.from(routes).pipe(smStream);
-
-    const data = await streamToPromise(smStream);
-
-    writeFileSync(path.join(publicDir, 'sitemap.xml'), data.toString());
+    return {
+      url: e?.replace(/index\.html$/, '').replace(/\/+$/, ''),
+      priority: 0.7,
+      changefreq: 'weekly',
+      lastmod
+    } as SitemapItem;
+  })
+  const smStream = new SitemapStream({ hostname: domain, lastmodDateOnly: true });
+  Readable.from(routes).pipe(smStream);
+
+  const data = await streamToPromise(smStream);
+
+  writeFileSync(path.join(publicDir, 'sitemap.xml'), data.toString());
+  const endTime = process.hrtime(startTime);
+  logger.log(`${routes.map((e) => colors.gray(`  ├─ ${e.url}`)).sort().join('\n')}`);
+  logger.info(`Generateed Sitemap ${routes.length} routes in ${(endTime[0] + (endTime[1] / 1e6) / 1000).toFixed(3)} seconds`)
+  logger.success(`Generated Sitemap at ${path.join(publicDir, 'sitemap.xml')}`);
 }