Node.jsexpress.json() parse Content-Type application/json thành req.body object — built-in từ Express 4.16+, không cần body-parser riêng. express.urlencoded({ extended: true }) parse HTML form data (application/x-www-form-urlencoded); extended: true dùng qs library cho phép nested objects, extended: false dùng querystring chỉ flat.
- Size limit mặc định 100kb — thay đổi:
express.json({ limit: '10mb' }). - Security: large payloads gây DoS — luôn set limit hợp lý, không để mặc định cho upload endpoint.
- Custom content types:
express.json({ type: 'application/vnd.api+json' }). - Raw parser:
express.raw({ type: 'application/octet-stream' })cho binary. - Text parser:
express.text()cho plain text webhooks. - Lưu ý:
express.json()không parse multipart/form-data (file upload) — cầnmulterriêng. - Nếu
req.bodylà undefined, kiểm tra middleware đã được đăng ký chưa và đúng thứ tự chưa.
express.json() parses Content-Type application/json into a req.body object — built into Express 4.16+, no separate body-parser package needed. express.urlencoded({ extended: true }) parses HTML form data (application/x-www-form-urlencoded); extended: true uses the qs library allowing nested objects, extended: false uses querystring for flat data only.
- Default size limit is 100KB — change with:
express.json({ limit: '10mb' }). - Security: large payloads can cause DoS — always set a reasonable limit, especially on upload endpoints.
- Custom content types:
express.json({ type: 'application/vnd.api+json' }). - Raw parser:
express.raw({ type: 'application/octet-stream' })for binary data. - Text parser:
express.text()for plain text webhooks.
Pitfall: express.json() does NOT parse multipart/form-data (file uploads) — you need multer for that.