Because it’s a promise, you know exactly when the data transfer is done.
For advanced use cases, a can intercept fetch requests. While it can’t easily tell the "main thread" that a background download is finished, it can be used to track the bytes passing through the network layer, offering a way to create custom progress bars even for standard links. Which one should you use?
if you are working with an older backend and just need a simple "Download Started" notification. browser download complete event javascript
For modern browsers (Chrome, Edge), the provides a much more robust way to handle files. By using showSaveFilePicker() , you can get a "handle" on the file. While it still doesn't give a "progress finished" event in the traditional sense, it allows you to write the stream directly to the disk, giving you a definitive point where the close() method is called. Method 4: Service Workers
While a browser.onDownloadComplete event doesn't exist in the JavaScript spec, the combined with Object URLs is the modern standard for tracking file delivery. It gives you the hooks you need to provide a seamless, interactive user experience. Because it’s a promise, you know exactly when
if you want to show a loading spinner before the file appears in the browser's download bar.
if the file is very large (hundreds of MBs), as fetch stores the file in the browser's memory first, which can crash tabs on mobile devices. Which one should you use
You send this token to the server as a query parameter.