Image upload with preview and Rails Direct Upload

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Direct uploads to cloud storage bypass the Rails server, improving performance and reducing server load. I use ActiveStorage's Direct Upload feature to get presigned URLs from Rails, then upload files directly to S3 from the browser. The React component shows image previews using FileReader API before upload, displays upload progress, and handles errors gracefully. The DirectUpload class from @rails/activestorage manages the upload process and provides progress callbacks. After successful upload, I submit the signed blob ID to Rails to attach it to a record. This pattern works for avatars, post images, or any file uploads where immediate server processing isn't required.