Q1. How do you serve static files (CSS, images) in Node.js?
Create a handler that reads files from a public directory. Example:
if (req.url.startsWith('/static/')) { const filePath = path.join(__dirname, 'public', req.url.slice(8)); fs.readFile(filePath, (err, data) => { if (err) { res.statusCode = 404; res.end(); } else { res.end(data); } }); }Q2. How do you determine the MIME type for static files?
Map file extensions to MIME types. Example:
const mimeTypes = { '.html': 'text/html', '.css': 'text/css', '.js': 'application/javascript', '.png': 'image/png', '.jpg': 'image/jpeg', '.json': 'application/json' }; const ext = path.extname(filePath); const contentType = mimeTypes[ext] || 'application/octet-stream';Q3. How do you handle large static files efficiently?
Use streams instead of reading entire files into memory. Example:
const stream = fs.createReadStream(filePath); stream.pipe(res);Q4. How do you implement caching for static files?
Set Cache-Control headers. Example:
res.setHeader('Cache-Control', 'public, max-age=86400'); // 1 dayQ5. What security considerations for static file serving?
Prevent directory traversal attacks by validating paths: ensure resolved path is within public directory. Example:
const resolvedPath = path.resolve(publicDir, filePath); if (!resolvedPath.startsWith(publicDir)) { return 403; }