You now understand frontend security.
XSS: Escape user input. Use framework protections. Add CSP.
CSRF: Use CSRF tokens and SameSite cookies.
Token storage: HttpOnly cookies preferred over localStorage.
Input validation: Client-side for UX, server-side for security.
HTTPS: Required. Add HSTS.
Dependencies: Audit regularly. Use lock files and SRI.
Authorization: Frontend hides UI. Backend enforces permissions.
Interview approach: Identify attack vectors for the specific design and propose mitigations.