File Upload Dropzone in JavaScript, Free with Live Demo

What this project does

• Drag and drop, click and paste
• Instant image previews
• Type and size checks with clear messages
• Per file progress bars
• Remove single files or clear all

How it works

1. Accept files three waysClick opens the file picker, dropping uses the drop event, and pasting reads clipboard files. All three go to one add function.
2. Check before uploadEach file is checked for type and size right away, so people see the problem before they wait for anything.
3. Preview without uploadingURL.createObjectURL shows a local image preview instantly. The URL is revoked when the file is removed.

The key JavaScript

This is the heart of the project. The full file has the rest, including the screen layout and error handling.

zone.addEventListener("drop", (e) => {
  e.preventDefault();
  for (const file of e.dataTransfer.files) {
    if (!["image/png", "image/jpeg", "application/pdf"].includes(file.type)) continue;
    if (file.size > 5 * 1024 * 1024) continue;           // 5 MB limit
    const img = new Image();
    img.src = URL.createObjectURL(file);                  // instant preview
    list.append(img);
  }
});
// real upload: fetch("/upload", { method: "POST", body: formData })

How to use it

1. Click Download HTML file above.
2. Open the file in a code editor, like VS Code.
3. Run it from a local server with npx serve . so the camera, microphone and AI features are allowed.
4. Change the text and colors, then upload it to GitHub Pages, Netlify or your own site. It is one file with no build step.

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