trying something

docs/docusaurus.config.js

@@ -81,6 +81,7 @@ const config = {
       /** @type {import('@docusaurus/preset-classic').Options} */
       ({
         docs: {
+          showLastUpdateTime: true,
           sidebarPath: require.resolve("./sidebars.js"),
           remarkPlugins: [
             [require("@docusaurus/remark-plugin-npm2yarn"), { sync: true }],

docs/src/theme/LastUpdated.js

@@ -0,0 +1,88 @@
+/* eslint-disable react/jsx-props-no-spreading, react/destructuring-assignment */
+import React from "react";
+
+const BASE_GIT_URL = "https://api.github.com/repos/langchain-ai/langchain/commits?path=docs"
+const LAST_UPDATED_ELEMENT_ID = "lc_last_updated"
+const INVALID_DATE_STRING = "Invalid date"
+/**
+ * 
+ * @param {Array<string>} urls 
+ * @returns {Promise<string | null>} The formatted date string or null if not found
+ */
+const fetchUrls = async (urls) => {
+  try {
+    const allResponses = await Promise.allSettled(urls.map(url => fetch(url)))
+    const allOkResponses = allResponses.filter(({ ok }) => ok);
+    const allData = await Promise.allSettled(allOkResponses.map(({ value }) => value.json()));
+    /** @type {null | string} */
+    let formattedDate = null;
+    allData.forEach((item) => {
+      if (formattedDate && formattedDate !== INVALID_DATE_STRING || !item || item.length === 0 || !item[0]?.commit?.author?.date) return;
+      const lastCommitDate = new Date(item[0]?.commit?.author?.date);
+      formattedDate = lastCommitDate.toLocaleDateString('en-US', {
+        year: 'numeric',
+        month: 'long',
+        day: 'numeric'
+      });
+    })
+    if (formattedDate !== INVALID_DATE_STRING) {
+      return formattedDate;
+    }
+  } catch (_) {
+    // no-op
+  }
+  return null;
+}
+
+const getAllPossibleUrls = (currentPath) => {
+  currentPath = currentPath.endsWith("/") ? currentPath.slice(0, -1) : currentPath;
+  return {
+    notebookPath: `${BASE_GIT_URL}${currentPath}.ipynb`,
+    notebookIndexPath: `${BASE_GIT_URL}${currentPath}/index.ipynb`,
+    mdPath: `${BASE_GIT_URL}${currentPath}.md`,
+    mdIndexPath: `${BASE_GIT_URL}${currentPath}/index.md`,
+    mdxPath: `${BASE_GIT_URL}${currentPath}.mdx`,
+    mdxIndexPath: `${BASE_GIT_URL}${currentPath}/index.mdx`,
+  }
+}
+
+/**
+ * NOTE: This component file should NEVER be updated as it overrides
+ * the default docusaurus LastUpdated component.
+ */
+export default function LastUpdated() {
+  const [lastUpdatedDate, setLastUpdatedDate] = React.useState(null);
+
+  React.useEffect(() => {
+    if (typeof window === "undefined") return;
+    try {
+      let currentPath = window.location.pathname;
+      const allUrls = getAllPossibleUrls(currentPath);
+      const { notebookPath, notebookIndexPath, ...rest } = allUrls;
+
+      fetchUrls([notebookPath, notebookIndexPath])
+        .then((date) => {
+          if (date) {
+            setLastUpdatedDate(date);
+          } else {
+            fetchUrls(rest)
+              .then((date) => {
+                if (date) {
+                  setLastUpdatedDate(date);
+                }
+              });
+          }
+        });
+    } catch (_) {
+      // no-op
+    }
+  }, [])
+
+  if (!lastUpdatedDate) return null;
+
+  return (
+    <div style={{ display: 'flex', justifyContent: 'flex-end' }} id={LAST_UPDATED_ELEMENT_ID}>
+      <p style={{ fontSize: 13.3333 }}><i>Last updated on <strong>{lastUpdatedDate}</strong></i></p>
+    </div>
+  );
+}