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diff --git a/src/templates/assets/javascripts/integrations/sitemap/index.ts b/src/templates/assets/javascripts/integrations/sitemap/index.ts
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+/*
+ * Copyright (c) 2016-2023 Martin Donath <martin.donath@squidfunk.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+import {
+  EMPTY,
+  Observable,
+  catchError,
+  defaultIfEmpty,
+  map,
+  of,
+  tap
+} from "rxjs"
+
+import { configuration } from "~/_"
+import { getElements, requestXML } from "~/browser"
+
+/* ----------------------------------------------------------------------------
+ * Types
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Sitemap, i.e. a list of URLs
+ */
+export type Sitemap = string[]
+
+/* ----------------------------------------------------------------------------
+ * Helper functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Preprocess a list of URLs
+ *
+ * This function replaces the `site_url` in the sitemap with the actual base
+ * URL, to allow instant navigation to work in occasions like Netlify previews.
+ *
+ * @param urls - URLs
+ *
+ * @returns URL path parts
+ */
+function preprocess(urls: Sitemap): Sitemap {
+  if (urls.length < 2)
+    return [""]
+
+  /* Take the first two URLs and remove everything after the last slash */
+  const [root, next] = [...urls]
+    .sort((a, b) => a.length - b.length)
+    .map(url => url.replace(/[^/]+$/, ""))
+
+  /* Compute common prefix */
+  let index = 0
+  if (root === next)
+    index = root.length
+  else
+    while (root.charCodeAt(index) === next.charCodeAt(index))
+      index++
+
+  /* Remove common prefix and return in original order */
+  return urls.map(url => url.replace(root.slice(0, index), ""))
+}
+
+/* ----------------------------------------------------------------------------
+ * Functions
+ * ------------------------------------------------------------------------- */
+
+/**
+ * Fetch the sitemap for the given base URL
+ *
+ * @param base - Base URL
+ *
+ * @returns Sitemap observable
+ */
+export function fetchSitemap(base?: URL): Observable<Sitemap> {
+  const cached = __md_get<Sitemap>("__sitemap", sessionStorage, base)
+  if (cached) {
+    return of(cached)
+  } else {
+    const config = configuration()
+    return requestXML(new URL("sitemap.xml", base || config.base))
+      .pipe(
+        map(sitemap => preprocess(getElements("loc", sitemap)
+          .map(node => node.textContent!)
+        )),
+        catchError(() => EMPTY), // @todo refactor instant loading
+        defaultIfEmpty([]),
+        tap(sitemap => __md_set("__sitemap", sitemap, sessionStorage, base))
+      )
+  }
+}