⚡ Bolt: [performance improvement] Precalculate Derived Render Properties

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2024-05-24 - Pre-calculate Derived Properties
+**Learning:** In `script.js`, filtering lists repeatedly (e.g., `renderPDFs` on each keystroke) can be expensive if we perform lowercasing, date parsing, and regex testing on the fly for every document. We can optimize this by doing an upfront calculation step `prepareSearchIndex` right after loading the database to append derived properties (`_searchStr`, `_isNew`, `_formattedDate`) directly to the documents.
+**Action:** When filtering objects, if you see properties being derived dynamically using methods like `String.toLowerCase()` or `Date.toLocaleDateString()` inside loops, precalculate them beforehand when the data is initialized.

script.js

@@ -338,6 +338,25 @@ function getAdData(slotName) {
 /* =========================================
    5. DATA LOADING WITH CACHING
    ========================================= */
+function prepareSearchIndex(data) {
+    const now = new Date();
+    data.forEach(pdf => {
+        // Pre-calculate search string
+        pdf._searchStr = `${pdf.title || ''} ${pdf.description || ''} ${pdf.category || ''} ${pdf.author || ''}`.toLowerCase();
+
+        // Handle Firestore Timestamp or string
+        let dateObj = pdf.uploadDate && typeof pdf.uploadDate.toDate === 'function'
+            ? pdf.uploadDate.toDate()
+            : new Date(pdf.uploadDate);
+
+        // Pre-calculate derived values to avoid per-render overhead
+        pdf._isNew = (now - dateObj) < (7 * 24 * 60 * 60 * 1000);
+        pdf._formattedDate = dateObj.toLocaleDateString('en-US', {
+            year: 'numeric', month: 'short', day: 'numeric'
+        });
+    });
+}
+
 function renderSemesterTabs() {
     const container = document.getElementById('semesterTabsContainer');
     if (!container) return;
@@ -454,6 +473,7 @@ async function loadPDFDatabase() {
 
         if (shouldUseCache) {
             pdfDatabase = cachedData;
+            prepareSearchIndex(pdfDatabase);
             // --- FIX: CALL THIS TO POPULATE UI ---
             syncClassSwitcher();
             renderSemesterTabs();
@@ -477,6 +497,8 @@ async function loadPDFDatabase() {
             data: pdfDatabase
         }));
 
+        prepareSearchIndex(pdfDatabase);
+
         // --- FIX: CALL THIS TO POPULATE UI ---
         syncClassSwitcher();
         renderPDFs();
@@ -905,26 +927,19 @@ function renderPDFs() {
 
     // Locate renderPDFs() in script.js and update the filter section
     const filteredPdfs = pdfDatabase.filter(pdf => {
-        const matchesSemester = pdf.semester === currentSemester;
-
-        // 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;
+        if (pdf.semester !== currentSemester) return false;
 
-        let matchesCategory = false;
         if (currentCategory === 'favorites') {
-            matchesCategory = favorites.includes(pdf.id);
-        } else {
-            matchesCategory = currentCategory === 'all' || pdf.category === currentCategory;
+            if (!favorites.includes(pdf.id)) return false;
+        } else 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);
+        // Fast search using pre-calculated property
+        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 +1009,8 @@ 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
+    // Use pre-calculated value or fallback
+    const isNew = pdf._isNew !== undefined ? pdf._isNew : (new Date() - new Date(pdf.uploadDate)) < (7 * 24 * 60 * 60 * 1000);
 
     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>`
@@ -1010,8 +1024,8 @@ 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', {
+    // Use pre-calculated formatted date or fallback
+    const formattedDate = pdf._formattedDate || new Date(pdf.uploadDate).toLocaleDateString('en-US', {
         year: 'numeric', month: 'short', day: 'numeric'
     });