Add selected file thumbnails

src/public/upload.css

@@ -223,29 +223,65 @@ h1 {
   margin: 0;
   padding: 0;
   list-style: none;
+  max-height: 265px;
+  overflow-y: auto;
+  overscroll-behavior: contain;
+  padding-right: 4px;
 }
 
 .file-list li {
   display: grid;
-  grid-template-columns: minmax(0, 1fr) auto;
+  grid-template-columns: minmax(0, 1fr) 64px;
-  gap: 12px;
+  min-height: 68px;
+  gap: 14px;
   align-items: center;
+  padding: 6px 0;
   color: #4f4f4f;
   font-family: "Apple SD Gothic Neo", "Malgun Gothic", system-ui, sans-serif;
   font-size: 13px;
 }
 
-.file-list span:first-child {
+.file-list__meta {
+  min-width: 0;
+}
+
+.file-list__meta span {
+  display: block;
+}
+
+.file-list__meta span:first-child {
   overflow: hidden;
   text-overflow: ellipsis;
   white-space: nowrap;
 }
 
-.file-list span:last-child {
+.file-list__meta span:last-child {
+  margin-top: 5px;
   color: #87928f;
   font-size: 12px;
 }
 
+.file-list__preview {
+  display: grid;
+  place-items: center;
+  width: 64px;
+  aspect-ratio: 1;
+  overflow: hidden;
+  border-radius: 6px;
+  background: #f7f8f6;
+  color: #8aa69f;
+  font-size: 11px;
+  font-weight: 700;
+  letter-spacing: 0.08em;
+}
+
+.file-list__preview img,
+.file-list__preview video {
+  width: 100%;
+  height: 100%;
+  object-fit: cover;
+}
+
 .upload-status {
   min-height: 22px;
   margin: 12px 0 0;

src/public/upload.html

@@ -55,6 +55,7 @@
       const list = form.querySelector(".file-list");
       const status = form.querySelector(".upload-status");
       const thanks = document.querySelector(".thank-you");
+      let previewUrls = [];
       submit.disabled = true;
 
       const formatBytes = (bytes) => {
@@ -68,8 +69,14 @@
         status.dataset.type = type;
       };
 
+      const clearPreviews = () => {
+        previewUrls.forEach((url) => URL.revokeObjectURL(url));
+        previewUrls = [];
+      };
+
       input?.addEventListener("change", () => {
         const files = Array.from(input.files || []);
+        clearPreviews();
         list.replaceChildren();
 
         if (files.length === 0) {
@@ -81,11 +88,34 @@
 
         files.forEach((file) => {
           const item = document.createElement("li");
+          const meta = document.createElement("div");
           const name = document.createElement("span");
           const size = document.createElement("span");
+          const preview = document.createElement("div");
+          const previewUrl = URL.createObjectURL(file);
+
+          previewUrls.push(previewUrl);
+          meta.className = "file-list__meta";
+          preview.className = "file-list__preview";
           name.textContent = file.name;
           size.textContent = formatBytes(file.size);
-          item.append(name, size);
+          if (file.type.startsWith("video/")) {
+            const video = document.createElement("video");
+            video.src = previewUrl;
+            video.muted = true;
+            video.playsInline = true;
+            video.preload = "metadata";
+            preview.append(video);
+          } else if (file.type.startsWith("image/")) {
+            const image = document.createElement("img");
+            image.src = previewUrl;
+            image.alt = "";
+            preview.append(image);
+          } else {
+            preview.textContent = "FILE";
+          }
+          meta.append(name, size);
+          item.append(meta, preview);
           list.append(item);
         });