21Twelve interview questions

I got a chance through some consultancy. They asked me about following in technical round. 1) CSS Box sizing Flex Responsiveness display :none v/s visibility : hidden v/s opacity :0 2) Javascript Var, let, const this keyword regular function vs arrow function map vs for-each 3) React lifecycle useEffect in detail Redux class based v/s functional components useCallback useMemo useState. Followed by output of few code snippets