Convert the Excel byte array to a Base64 string and return it in a JSON object (e.g., { "fileName": "data.xlsx", "fileContent": "base64_string..." } ).

This method allows you to receive binary data directly and trigger a download via a virtual link. It is the most robust way to handle dynamic file generation. javascript

Use a utility function like base64toBlob to reconstruct the file before downloading. Best Practices & Troubleshooting Download a file asynchronously using Ajax - Stack Overflow

$.ajax({ url: '/your-server-endpoint', method: 'POST', // Use POST if sending filters/data data: JSON.stringify({ reportId: 123 }), contentType: 'application/json', xhrFields: { responseType: 'blob' // Essential: Tells the browser to handle binary data }, success: function (data, status, xhr) { // 1. Create a URL for the binary data var blob = new Blob([data], { type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet' }); var downloadUrl = URL.createObjectURL(blob); // 2. Create a hidden anchor element to trigger download var a = document.createElement("a"); a.href = downloadUrl; a.download = "Report.xlsx"; // Set your desired filename document.body.appendChild(a); a.click(); // 3. Cleanup: remove the link and revoke the URL to free memory setTimeout(function () { URL.revokeObjectURL(downloadUrl); $(a).remove(); }, 100); }, error: function () { alert('Download failed.'); } }); Use code with caution. Method 2: Handling Older Browsers (Base64)

By default, jQuery treats all responses as strings. If you try to download an Excel file using a standard $.ajax call, the browser will attempt to interpret the binary stream as text, resulting in a corrupted "garbled" file. Method 1: The Modern "Blob" Approach (Recommended)

If your environment has issues handling Blobs directly, you can return a from the server. The client-side script then converts this back to a file.

Downloading Excel files through is a common requirement for modern web applications that need to generate reports dynamically without refreshing the page. While standard AJAX is designed for text-based data (like JSON or HTML), handling binary files like .xlsx requires specific configurations to prevent data corruption. Why Standard jQuery AJAX Fails with Files