From be46fa6794dc38f967118fc4e7bb9e025db28bf6 Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Wed, 4 Mar 2026 13:47:42 +0000
Subject: [PATCH] perf: cache favorites to prevent synchronous localStorage
 reads

Implements an in-memory cache for the user's favorites list to avoid executing `localStorage.getItem` and `JSON.parse` synchronously during the high-frequency `renderPDFs` search filtering loop. Updates `toggleFavorite` to update both the cache and persistent storage. Adds a learning entry to the bolt journal.

Co-authored-by: MrAlokTech <107493955+MrAlokTech@users.noreply.github.com>
---
 .jules/bolt.md |  4 ++++
 script.js      | 10 +++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)
 create mode 100644 .jules/bolt.md

diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..e48acac
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,4 @@
+
+## 2026-03-04 - [Caching localStorage for High-Frequency Loops]
+**Learning:** Found a performance bottleneck where `localStorage.getItem` and `JSON.parse()` were being called synchronously inside `getFavorites()`, which was executed on every keystroke during `renderPDFs` search filtering.
+**Action:** Always cache expensive synchronous operations (like `localStorage` parsing) in a variable when they are accessed in high-frequency rendering or filtering loops. Ensure state updating functions like `toggleFavorite` update both the cache and persistent storage.
diff --git a/script.js b/script.js
index bdc06f3..c79d55d 100644
--- a/script.js
+++ b/script.js
@@ -1315,9 +1315,14 @@ async function handleCommentSubmit(e) {
 /* =========================================
    10. EXTRAS (THEME, FAVORITES, EASTER EGGS)
    ========================================= */
+// ⚡ Bolt Optimization: Cache favorites to avoid synchronous localStorage reads and JSON.parse on every render
+let favoritesCache = null;
+
 function getFavorites() {
+    if (favoritesCache !== null) return favoritesCache;
     const stored = localStorage.getItem('classNotesFavorites');
-    return stored ? JSON.parse(stored) : [];
+    favoritesCache = stored ? JSON.parse(stored) : [];
+    return favoritesCache;
 }
 
 function toggleFavorite(event, pdfId) {
@@ -1336,6 +1341,9 @@ function toggleFavorite(event, pdfId) {
         favorites.push(pdfId);
         showToast('Added to saved notes');
     }
+
+    // Update cache before saving
+    favoritesCache = favorites;
     localStorage.setItem('classNotesFavorites', JSON.stringify(favorites));
     renderPDFs();
 }