⚡ Bolt: Pre-calculate derived properties for faster list rendering

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2024-05-24 - [List Rendering Optimization]
+**Learning:** Pre-calculating derived properties `_searchStr`, `_formattedDate` and `_isNew` and using `Intl.DateTimeFormat` on load is way faster than inline computations during frequent filtering and rendering loop for large list. Early return with simplified conditionals in filters also leads to considerable speed up.
+**Action:** Always pre-calculate derived search properties for list and add them directly into the object immediately after data fetches.

script.js

@@ -338,6 +338,35 @@ function getAdData(slotName) {
 /* =========================================
    5. DATA LOADING WITH CACHING
    ========================================= */
+
+/**
+ * ⚡ BOLT OPTIMIZATION: Pre-calculate derived properties to avoid expensive
+ * inline calculations during frequent render/filter loops.
+ */
+function prepareSearchIndex(pdfs) {
+    const now = new Date().getTime();
+    const formatter = new Intl.DateTimeFormat('en-US', {
+        year: 'numeric', month: 'short', day: 'numeric'
+    });
+
+    for (let i = 0; i < pdfs.length; i++) {
+        const pdf = pdfs[i];
+
+        // Pre-calculate full search string
+        pdf._searchStr = `${pdf.title || ''} ${pdf.description || ''} ${pdf.category || ''} ${pdf.author || ''}`.toLowerCase();
+
+        // Pre-calculate date formatting if valid
+        const uploadDateObj = new Date(pdf.uploadDate);
+        if (!isNaN(uploadDateObj.getTime())) {
+            pdf._formattedDate = formatter.format(uploadDateObj);
+            pdf._isNew = (now - uploadDateObj.getTime()) < (7 * 24 * 60 * 60 * 1000);
+        } else {
+            pdf._formattedDate = 'Unknown Date';
+            pdf._isNew = false;
+        }
+    }
+}
+
 function renderSemesterTabs() {
     const container = document.getElementById('semesterTabsContainer');
     if (!container) return;
@@ -454,6 +483,7 @@ async function loadPDFDatabase() {
 
         if (shouldUseCache) {
             pdfDatabase = cachedData;
+            prepareSearchIndex(pdfDatabase);
             // --- FIX: CALL THIS TO POPULATE UI ---
             syncClassSwitcher();
             renderSemesterTabs();
@@ -477,6 +507,8 @@ async function loadPDFDatabase() {
             data: pdfDatabase
         }));
 
+        prepareSearchIndex(pdfDatabase);
+
         // --- FIX: CALL THIS TO POPULATE UI ---
         syncClassSwitcher();
         renderPDFs();
@@ -905,26 +937,32 @@ 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);
-        } 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);
+        if (searchTerm) {
+            // Use pre-calculated search string or fallback
+            if (pdf._searchStr) {
+                if (!pdf._searchStr.includes(searchTerm)) return false;
+            } else {
+                const matchesSearch = pdf.title.toLowerCase().includes(searchTerm) ||
+                    pdf.description.toLowerCase().includes(searchTerm) ||
+                    pdf.category.toLowerCase().includes(searchTerm) ||
+                    pdf.author.toLowerCase().includes(searchTerm);
+                if (!matchesSearch) return false;
+            }
+        }
 
-        // Update return statement to include matchesClass
-        return matchesSemester && matchesClass && matchesCategory && matchesSearch;
+        return true;
     });
 
     updatePDFCount(filteredPdfs.length);
@@ -994,9 +1032,12 @@ 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
+    let isNew = pdf._isNew;
+    if (isNew === undefined) {
+        const uploadDateObj = new Date(pdf.uploadDate);
+        const timeDiff = new Date() - uploadDateObj;
+        isNew = timeDiff < (7 * 24 * 60 * 60 * 1000); // 7 days
+    }
 
     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 +1052,12 @@ 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'
-    });
+    let formattedDate = pdf._formattedDate;
+    if (!formattedDate) {
+        formattedDate = new Date(pdf.uploadDate).toLocaleDateString('en-US', {
+            year: 'numeric', month: 'short', day: 'numeric'
+        });
+    }
 
     // Uses global escapeHtml() now