Q1. How do you build a REST API with pure Node.js?
Create an HTTP server, parse the request method and URL, implement CRUD operations. Example:
if (req.method === 'GET' && req.url === '/api/users') { // return users } else if (req.method === 'POST' && req.url === '/api/users') { // parse body, create user }Q2. How do you parse JSON request bodies for API endpoints?
Collect data chunks as described earlier, then after 'end' event, parse with JSON.parse(body). Handle errors for invalid JSON. Example:
let body = ''; req.on('data', chunk => { body += chunk; }).on('end', () => { try { const data = JSON.parse(body); // process } catch (err) { res.statusCode = 400; res.end('Invalid JSON'); } });Q3. How do you implement routing for REST API?
Create a routing table mapping patterns to handlers. For resource-based routing, use patterns like '/api/users/:id'. Extract ID from URL. Example:
const match = req.url.match(/^/api/users/(d+)$/); if (match) { const id = match[1]; // handle /api/users/123 }Q4. How do you send proper HTTP status codes for API responses?
Set res.statusCode appropriately: 200 OK, 201 Created, 400 Bad Request, 401 Unauthorized, 403 Forbidden, 404 Not Found, 500 Internal Server Error. Also set Content-Type: application/json. Example:
res.statusCode = 201; res.setHeader('Content-Type', 'application/json'); res.end(JSON.stringify(newUser));Q5. How do you handle CORS in a pure Node.js API?
Set CORS headers on responses:
res.setHeader('Access-Control-Allow-Origin', '*'); res.setHeader('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE'); res.setHeader('Access-Control-Allow-Headers', 'Content-Type');