try const response = await fetch('/api/upload', method: 'POST', body: formData ); const result = await response.json(); alert('Upload success: ' + result.file.storedName); catch (err) console.error(err); alert('Upload failed');

// Upload route app.post('/api/upload', upload.single('file'), (req, res) => if (!req.file) return res.status(400).json( error: 'No file uploaded' );

const upload = multer( storage: storage, limits: fileSize: 10 * 1024 * 1024 , // 10MB fileFilter: fileFilter );

); );

</script> If you give me more details about (is it a military/logistics app? a gaming tool? a security tool?), I can tailor the file upload logic exactly to your use case — including encryption, chunked uploads, metadata extraction, or cloud integration.