⚡ Bolt: [performance improvement] Caching search indices and early returns

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2026-03-18 - Caching Search Index and Optimizing Loops
+**Learning:** Pre-calculating derived fields (like lowercased search strings, `isNew`, `formattedDate`) on initial list load dramatically improves the performance of frequent operations like searching/filtering by avoiding redundant calculations on every render. Also, grouping boolean variables (`a && b && c`) in array filters is less efficient than explicit early returns (`if (!a) return false;`), which bypasses further evaluations immediately when a basic condition fails.
+**Action:** When working with large lists or frequent render cycles, always identify expensive string/date operations that can be moved upstream (to data load/init time) and favor explicit early returns for cheap equality checks.

script.js

@@ -454,6 +454,7 @@ async function loadPDFDatabase() {
 
         if (shouldUseCache) {
             pdfDatabase = cachedData;
+            prepareSearchIndex(pdfDatabase);
             // --- FIX: CALL THIS TO POPULATE UI ---
             syncClassSwitcher();
             renderSemesterTabs();
@@ -472,6 +473,8 @@ async function loadPDFDatabase() {
             pdfDatabase.push({ id: doc.id, ...doc.data() });
         });
 
+        prepareSearchIndex(pdfDatabase);
+
         localStorage.setItem(CACHE_KEY, JSON.stringify({
             timestamp: new Date().getTime(),
             data: pdfDatabase
@@ -503,6 +506,34 @@ function hidePreloader() {
     }
 }
 
+window.prepareSearchIndex = function prepareSearchIndex(dataList) {
+    const now = new Date();
+    dataList.forEach(pdf => {
+        // Handle Firestore Timestamp vs regular ISO string
+        let uploadDateObj;
+        if (pdf.uploadDate && typeof pdf.uploadDate.toDate === 'function') {
+            uploadDateObj = pdf.uploadDate.toDate();
+        } else {
+            uploadDateObj = new Date(pdf.uploadDate);
+        }
+
+        const timeDiff = now - uploadDateObj;
+        pdf._isNew = timeDiff < (7 * 24 * 60 * 60 * 1000); // 7 days
+
+        pdf._formattedDate = uploadDateObj.toLocaleDateString('en-US', {
+            year: 'numeric', month: 'short', day: 'numeric'
+        });
+
+        // Pre-calculate lowercased search string
+        const title = pdf.title || '';
+        const desc = pdf.description || '';
+        const cat = pdf.category || '';
+        const author = pdf.author || '';
+        pdf._searchStr = `${title} ${desc} ${cat} ${author}`.toLowerCase();
+    });
+}
+
+
 /* =========================================
    6. MAINTENANCE & HOLIDAYS
    ========================================= */
@@ -905,26 +936,21 @@ function renderPDFs() {
 
     // Locate renderPDFs() in script.js and update the filter section
     const filteredPdfs = pdfDatabase.filter(pdf => {
-        const matchesSemester = pdf.semester === currentSemester;
+        if (pdf.semester !== currentSemester) return false;
 
         // NEW: Check if the PDF class matches the UI's current class selection
         // Note: If old documents don't have this field, they will be hidden.
-        const matchesClass = pdf.class === currentClass;
+        if (pdf.class !== currentClass) return false;
 
-        let matchesCategory = false;
         if (currentCategory === 'favorites') {
-            matchesCategory = favorites.includes(pdf.id);
+            if (!favorites.includes(pdf.id)) return false;
         } else {
-            matchesCategory = currentCategory === 'all' || pdf.category === currentCategory;
+            if (currentCategory !== 'all' && pdf.category !== currentCategory) return false;
         }
 
-        const matchesSearch = pdf.title.toLowerCase().includes(searchTerm) ||
-            pdf.description.toLowerCase().includes(searchTerm) ||
-            pdf.category.toLowerCase().includes(searchTerm) ||
-            pdf.author.toLowerCase().includes(searchTerm);
+        if (searchTerm && (!pdf._searchStr || !pdf._searchStr.includes(searchTerm))) return false;
 
-        // Update return statement to include matchesClass
-        return matchesSemester && matchesClass && matchesCategory && matchesSearch;
+        return true;
     });
 
     updatePDFCount(filteredPdfs.length);
@@ -994,9 +1020,7 @@ function createPDFCard(pdf, favoritesList, index = 0, highlightRegex = null) {
     const heartIconClass = isFav ? 'fas' : 'far';
     const btnActiveClass = isFav ? 'active' : '';
 
-    const uploadDateObj = new Date(pdf.uploadDate);
-    const timeDiff = new Date() - uploadDateObj;
-    const isNew = timeDiff < (7 * 24 * 60 * 60 * 1000); // 7 days
+    const isNew = pdf._isNew;
 
     const newBadgeHTML = isNew
         ? `<span style="background:var(--error-color); color:white; font-size:0.6rem; padding:2px 6px; border-radius:4px; margin-left:8px; vertical-align:middle;">NEW</span>`
@@ -1011,9 +1035,7 @@ function createPDFCard(pdf, favoritesList, index = 0, highlightRegex = null) {
     const categoryIcon = categoryIcons[pdf.category] || 'fa-file-pdf';
 
     // Formatting Date
-    const formattedDate = new Date(pdf.uploadDate).toLocaleDateString('en-US', {
-        year: 'numeric', month: 'short', day: 'numeric'
-    });
+    const formattedDate = pdf._formattedDate;
 
     // Uses global escapeHtml() now