Q1. How do you handle file uploads in a raw Node.js HTTP server?
Parse multipart/form-data manually, which is complex. Better to use modules like formidable or multer. With formidable:
const form = new formidable.IncomingForm(); form.parse(req, (err, fields, files) => { console.log(files.upload.path); });Q2. How do you create an HTML form for file upload?
Create an HTML form with enctype="multipart/form-data":
Q3. How do you save uploaded files to disk?
With formidable, after parsing, the file is in a temporary location. Use fs.rename or fs.copyFile to move it:
const oldPath = files.upload.filepath; const newPath = path.join(__dirname, 'uploads', files.upload.originalFilename); fs.rename(oldPath, newPath, (err) => { ... });Q4. How do you validate uploaded files?
Check file size, type, and extension. With formidable, you can use options:
const form = formidable({ maxFileSize: 5 * 1024 * 1024, filter: ({ mimetype }) => { return mimetype && mimetype.includes('image'); } });Q5. How do you handle large file uploads efficiently?
Use streams to avoid loading entire file into memory. With formidable, it already streams to disk. For custom implementation, pipe the request to a write stream:
req.pipe(fs.createWriteStream('upload.txt'))