refactor: ♻️ clean up gallery code

- cast images collection to array for clarity in galleryObserver
- shorten debounce function
- do not destructure track object for isAtEnd (no space savings or readability improvements)
- remove unused argument in updateActiveStates
- call functions directly during page initialization

src/components/ref-gallery.webc

@@ -1,7 +1,7 @@
 <script>
   const gallery = document.querySelector('.gallery');
   const track = gallery.querySelector('.track');
-  const images = gallery.querySelectorAll('.track > *');
+  const images = Array.from(gallery.querySelectorAll('.track > *'));
   const nav = gallery.querySelector('.gallery-nav');
   const prevButton = gallery.querySelector('button.prev');
   const nextButton = gallery.querySelector('button.next');
@@ -9,24 +9,16 @@
   const TOLERANCE = 2;
 
   const debounce = (fn, delay = 300) => {
-    let timer = 0;
-    const debounced = (...args) => {
-      if (!args) args = [];
+    let timer;
+    return function (...args) {
       clearTimeout(timer);
-
-      timer = setTimeout(() => {
-        fn.apply(fn, args);
-      }, delay);
+      timer = setTimeout(() => fn.apply(fn, args), delay);
     };
-
-    return debounced;
   };
 
   const isAtStart = () => Math.floor(track.scrollLeft) <= TOLERANCE;
-  const isAtEnd = () => {
-    const { scrollLeft, offsetWidth, scrollWidth } = track;
-    return Math.abs(scrollLeft + offsetWidth - scrollWidth) <= TOLERANCE;
-  };
+  const isAtEnd = () =>
+    Math.abs(track.scrollLeft + track.offsetWidth - track.scrollWidth) <= TOLERANCE;
 
   const updateAriaCurrent = (element, index) => {
     currentIndex === index
@@ -34,7 +26,7 @@
       : element.removeAttribute('aria-current');
   };
 
-  const updateActiveStates = (index) => {
+  const updateActiveStates = () => {
     images.forEach(updateAriaCurrent);
     nav.querySelectorAll('.indicator-btn').forEach(updateAriaCurrent);
     prevButton.disabled = isAtStart();
@@ -49,7 +41,7 @@
     currentIndex = index;
     images[index].scrollIntoView({ behavior: 'smooth', block: 'nearest', inline: 'center' });
 
-    updateActiveStates(index);
+    updateActiveStates();
   };
 
   const prev = () => scrollToIndex(currentIndex - 1);
@@ -62,10 +54,10 @@
     (entries) => {
       entries.forEach((entry) => {
         if (entry.isIntersecting && entry.intersectionRatio >= 0.75) {
-          const index = [...images].indexOf(entry.target);
+          const index = images.indexOf(entry.target);
           if (index !== -1) {
             currentIndex = index;
-            updateActiveStates(currentIndex);
+            updateActiveStates();
           }
         }
       });
@@ -92,14 +84,14 @@
       nav.appendChild(btn);
     });
 
-    updateActiveStates(0);
+    updateActiveStates();
   };
 
   images.forEach((el) => galleryObserver.observe(el));
   prevButton.addEventListener('click', prev);
   nextButton.addEventListener('click', next);
-  track.addEventListener('scroll', () => debounce(updateActiveStates(currentIndex)));
-  document.addEventListener('DOMContentLoaded', () => initializeGallery());
+  track.addEventListener('scroll', debounce(updateActiveStates, 100));
+  document.addEventListener('DOMContentLoaded', initializeGallery);
 </script>
 
 <section aria-label="Image gallery" webc:root="override">