feat: refine and finalize redesign

src/scripts/activeSectionTracker.ts

@@ -0,0 +1,64 @@
+export interface ActiveSectionTrackerOptions {
+  linkSelector: string;
+  sectionIdAttr?: string;
+  headerOffset?: number;
+  defaultToFirst?: boolean;
+}
+
+export function initActiveSectionTracker(
+  options: ActiveSectionTrackerOptions,
+): void {
+  const {
+    linkSelector,
+    sectionIdAttr = "data-section-id",
+    headerOffset = 100,
+    defaultToFirst = true,
+  } = options;
+
+  const links = document.querySelectorAll(linkSelector);
+  const sections: { id: string; element: Element }[] = [];
+
+  // Collect unique section IDs
+  const seenIds = new Set<string>();
+  links.forEach((link) => {
+    const id = link.getAttribute(sectionIdAttr);
+    if (id && !seenIds.has(id)) {
+      seenIds.add(id);
+      const section = document.getElementById(id);
+      if (section) {
+        sections.push({ id, element: section });
+      }
+    }
+  });
+
+  function updateActiveSection(): void {
+    let activeId: string | null = defaultToFirst ? sections[0]?.id : null;
+
+    for (const { id, element } of sections) {
+      const rect = element.getBoundingClientRect();
+      if (rect.top <= headerOffset) {
+        activeId = id;
+      }
+    }
+
+    links.forEach((link) => {
+      const linkId = link.getAttribute(sectionIdAttr);
+      link.classList.toggle("active", linkId === activeId);
+    });
+  }
+
+  // Update on scroll with throttling
+  let ticking = false;
+  window.addEventListener("scroll", () => {
+    if (!ticking) {
+      requestAnimationFrame(() => {
+        updateActiveSection();
+        ticking = false;
+      });
+      ticking = true;
+    }
+  });
+
+  // Initial update
+  updateActiveSection();
+}