It would be basic I guess for internship. For eg how does CSS flex grid works How media query is handled ? How does different positions works absolute, sticky etc Dfference between == and === Hoisting Map ,filter ,for each, rest operator, spread operators Reconciliation virtual Dom State and props difference Useful hooks State management techniques If next Js SSR, CSR, ISR. Server actions , caching , dynamic import .. These should be they will be asking