Server-side form validation vs client-side validation khi nào dùng cái nào?

Client-side validation: UX tốt hơn, instant feedback, giảm unnecessary server requests.

• KHÔNG thể thay thế server-side vì user có thể bypass.
• Server-side validation: bắt buộc cho security, validate business rules phức tạp, kiểm tra database constraints.
• Best practice: cả hai - client để UX, server để security và correctness.

Client-side validation: better UX, instant feedback, fewer unnecessary server requests.

• It CANNOT replace server-side validation because users can bypass it.
• Server-side validation: mandatory for security, enforcing complex business rules, and checking database constraints.
• Best practice: use both — client-side for UX, server-side for security and correctness.