Adds featured tab to web (#34405)

app/javascript/mastodon/hooks/useAccountId.ts

@@ -0,0 +1,37 @@
+import { useEffect } from 'react';
+
+import { useParams } from 'react-router';
+
+import { fetchAccount, lookupAccount } from 'mastodon/actions/accounts';
+import { normalizeForLookup } from 'mastodon/reducers/accounts_map';
+import { useAppDispatch, useAppSelector } from 'mastodon/store';
+
+interface Params {
+  acct?: string;
+  id?: string;
+}
+
+export function useAccountId() {
+  const { acct, id } = useParams<Params>();
+  const accountId = useAppSelector(
+    (state) =>
+      id ??
+      (state.accounts_map.get(normalizeForLookup(acct)) as string | undefined),
+  );
+
+  const account = useAppSelector((state) =>
+    accountId ? state.accounts.get(accountId) : undefined,
+  );
+  const isAccount = !!account;
+
+  const dispatch = useAppDispatch();
+  useEffect(() => {
+    if (!accountId) {
+      dispatch(lookupAccount(acct));
+    } else if (!isAccount) {
+      dispatch(fetchAccount(accountId));
+    }
+  }, [dispatch, accountId, acct, isAccount]);
+
+  return accountId;
+}