Start a setInterval in your JavaScript to poll the browser's cookies every 500ms, looking for that specific token.
Detecting when a browser receives a file download is a notorious challenge for web developers because modern browsers do not provide a native onDownload event for standard links. This security-focused design prevents websites from knowing too much about a user’s local file system.
This is the gold standard for tracking traditional downloads (e.g., clicking a link to a PDF or ZIP file). It works by coordinating a unique token between the client and server. detect when a browser receives a file download
However, there are several effective "hacks" and modern techniques to bridge this gap, ranging from server-side cookie tracking to advanced JavaScript APIs. 1. The Token & Cookie Method (Most Reliable)
As soon as the browser receives the file headers, the cookie is set. Your JavaScript detects it, clears the interval, and triggers a "Success" UI or hides the loading spinner. 2. The Fetch & Blob Approach (Best for Progress Tracking) Start a setInterval in your JavaScript to poll
Detect when user accepts to download a file - Stack Overflow
When a user clicks "Download," generate a unique ID (token) via JavaScript. This is the gold standard for tracking traditional
If you need to show a real-time progress bar, you cannot use a standard link. Instead, you must fetch the file data manually.