Detect When Browser Receives File Download [verified] Javascript Direct

The most accurate client-side solution relies on bypassing the standard anchor tag navigation. You request the data via the Fetch API, track the response completion within your code, and convert the finalized payload into an in-memory binary large object (Blob). javascript

Requires explicit backend synchronization. Will not work if your application blocks third-party cookies or enforces restrictive SameSite policies. Method 3: Tracking Exact Download Progress (XHR)

async function downloadAndDetectFile(fileUrl, fileName) { // 1. Show your UI loader or spinner updateUI('loading'); try { // 2. Fetch the file data directly const response = await fetch(fileUrl); if (!response.ok) throw new Error('Network response failure.'); const blob = await response.blob(); // 3. Trigger the file save dialog natively const downloadUrl = URL.createObjectURL(blob); const hiddenAnchor = document.createElement('a'); hiddenAnchor.href = downloadUrl; hiddenAnchor.download = fileName; document.body.appendChild(hiddenAnchor); hiddenAnchor.click(); // 4. Clean up memory allocations document.body.removeChild(hiddenAnchor); URL.revokeObjectURL(downloadUrl); // 5. This block executes exactly when the file is fully received updateUI('complete'); console.log("File download detection successful."); } catch (error) { console.error("Download failed:", error); updateUI('error'); } } Use code with caution. Pros & Cons detect when browser receives file download javascript

to detect when a browser receives a file download. When a server responds with a Content-Disposition: attachment header, the browser handles the stream internally, isolating the process from the standard DOM lifecycle.

function downloadWithPercentage(url) { const xhr = new XMLHttpRequest(); xhr.open('GET', url, true); xhr.responseType = 'blob'; xhr.addEventListener('progress', (event) => { if (event.lengthComputable) { const percentage = Math.round((event.loaded / event.total) * 100); document.getElementById('progress-bar').value = percentage; } }); xhr.addEventListener('load', () => { if (xhr.status === 200) { const blob = xhr.response; const link = document.createElement('a'); link.href = URL.createObjectURL(blob); link.download = 'archive.zip'; link.click(); updateStatus('Finished Processing!'); } }); xhr.send(); } Use code with caution. Technical Trade-Off Summary javascript - Detect when a browser receives a file download The most accurate client-side solution relies on bypassing

Zero JavaScript memory overhead; perfect for massive ZIP or video file deliveries. Will not work if your application blocks third-party

Method 2: Server Cookie Polling (Best for Large, Legacy, or Dynamic Files)