Animate episode thumbnails on hover

public/assets/app.js

@@ -130,7 +130,6 @@ function renderDetails(title) {
             <button id="editMetaBtn" type="button">Edit</button>
             <button id="fetchMetadataBtn" type="button">Metadata</button>
             <button id="makeThumbBtn" type="button">Thumbnail</button>
-            <button id="playAllBtn" class="primary" type="button">Play all</button>
           </div>
         </div>
         <div id="metaView" class="meta-view">
@@ -142,6 +141,9 @@ function renderDetails(title) {
         <div id="metaEditMount"></div>
       </div>
     </div>
+    <div class="episode-toolbar">
+      <button id="playAllBtn" class="primary" type="button">Play all</button>
+    </div>
     <div class="seasons">
       ${title.seasons.map(renderSeason).join("")}
     </div>
@@ -236,7 +238,14 @@ function renderSeason(season) {
         ${season.videos.map((video) => `
           <button class="episode" type="button" data-video-id="${escapeAttr(video.id)}">
             <span class="episode__thumb">
-              <img src="${escapeAttr(video.thumbnail)}" alt="" loading="lazy" onerror="this.hidden=true">
+              <img
+                src="${escapeAttr(video.thumbnail)}"
+                data-still="${escapeAttr(video.thumbnail)}"
+                data-animated="${escapeAttr(video.animatedThumbnail)}"
+                alt=""
+                loading="lazy"
+                onerror="this.hidden=true"
+              >
               <span class="episode__play">Play</span>
             </span>
             <span class="episode__name">${escapeHtml(video.name)}</span>
@@ -255,6 +264,23 @@ function flattenVideos(title) {
 function wireEpisodeCards(title) {
   const videos = flattenVideos(title);
   document.querySelectorAll("[data-video-id]").forEach((node) => {
+    const image = node.querySelector("img");
+    const showAnimated = () => {
+      if (image?.dataset.animated && image.src !== new URL(image.dataset.animated, window.location.href).href) {
+        image.hidden = false;
+        image.src = image.dataset.animated;
+      }
+    };
+    const showStill = () => {
+      if (image?.dataset.still && image.src !== new URL(image.dataset.still, window.location.href).href) {
+        image.hidden = false;
+        image.src = image.dataset.still;
+      }
+    };
+    node.addEventListener("mouseenter", showAnimated);
+    node.addEventListener("focus", showAnimated);
+    node.addEventListener("mouseleave", showStill);
+    node.addEventListener("blur", showStill);
     node.addEventListener("click", () => {
       const index = videos.findIndex((video) => video.id === node.dataset.videoId);
       startPlaylist(videos, Math.max(index, 0));